U.S. patent application number 16/325010 was filed with the patent office on 2019-10-17 for sealing composition.
This patent application is currently assigned to PRC-DeSoto International, Inc.. The applicant listed for this patent is PRC-DESOTO INTERNATIONAL, INC.. Invention is credited to Mary Lyn Chong LIM, Michael A. MAYO, Eric L. MORRIS, Brian C. OKERBERG, Gordon L. POST.
Application Number | 20190316261 16/325010 |
Document ID | / |
Family ID | 59677448 |
Filed Date | 2019-10-17 |
United States Patent
Application |
20190316261 |
Kind Code |
A1 |
MORRIS; Eric L. ; et
al. |
October 17, 2019 |
Sealing Composition
Abstract
Disclosed is a method of treating a substrate. The surface is
contacted with a sealing composition comprising a lithium cation;
and optionally, with conversion composition comprising a cation of
a lanthanide, a Group IIIB, and/or a Group IVB metal. The
conversion composition is applied to provide a film on the
substrate surface resulting in a level of the lanthanide, Group
IIIB metal, and/or Group IV metal thereon of at least 100 counts
greater than on a surface of a substrate that does not have the
film thereon as measured by X-ray fluorescence (measured using
X-Met 7500, Oxford Instruments; operating parameters 60 second
timed assay, 15 Kv, 45 .mu.A, filter 3, T(p)=1.5 .mu.s for
lanthanides, Group IIIB metals, and Group IVB metals except
zirconium; operating parameters 60 second timed assay, 40 Kv, 10
.mu.A, filter 4, T(p)=1.5 .mu.s for zirconium). A substrate
obtainable by the methods also is disclosed.
Inventors: |
MORRIS; Eric L.; (Murrieta,
CA) ; POST; Gordon L.; (Pittsburgh, PA) ;
MAYO; Michael A.; (Pittsburgh, PA) ; OKERBERG; Brian
C.; (Gibsonia, PA) ; LIM; Mary Lyn Chong;
(Allison Park, PA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
PRC-DESOTO INTERNATIONAL, INC. |
Sylmar |
CA |
US |
|
|
Assignee: |
PRC-DeSoto International,
Inc.
Sylmar
CA
|
Family ID: |
59677448 |
Appl. No.: |
16/325010 |
Filed: |
August 14, 2017 |
PCT Filed: |
August 14, 2017 |
PCT NO: |
PCT/US2017/046730 |
371 Date: |
February 12, 2019 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
62374199 |
Aug 12, 2016 |
|
|
|
62374188 |
Aug 12, 2016 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C01B 25/372 20130101;
C23C 22/66 20130101; C23C 22/56 20130101; C23C 22/12 20130101; C23C
22/83 20130101; C23C 22/73 20130101; C23C 22/78 20130101; C01B
25/37 20130101; C23C 22/13 20130101 |
International
Class: |
C23C 22/66 20060101
C23C022/66 |
Claims
1. A method of treating a substrate comprising: contacting at least
a portion of the substrate surface with a sealing composition
comprising a lithium cation; wherein the sealing composition is
applied to provide a layer of the dried sealing composition having
a thickness of 5 nm to 550 nm.
2. The method of claim 1, wherein the lithium cation is present in
the sealing composition in an amount of 5 ppm to 5500 ppm (as
lithium cation) based on total weight of the sealing
composition.
3. The method of claim 1, wherein the sealing composition further
comprises a carbonate source, a hydroxide source, or combinations
thereof.
4. The method of claim 1, wherein the sealing composition further
comprises a Group IA metal cation other than lithium, a Group VB
metal cation, a Group VIB metal cation, a corrosion inhibitor, an
indicator compound, or combinations thereof.
5. The method of claim 1, wherein the pH of the sealing composition
is 9.5 to 12.5.
6. The method of claim 1, wherein, following the contacting with
the sealing composition, the substrate is not rinsed with water
prior to contacting at least a portion of the substrate surface
with subsequent treatment compositions.
7. The method of claim 1, wherein the temperature of the sealing
composition is 40.degree. F. to 160.degree. F.
8. The method of claim 1, wherein the contacting is for 1 second to
15 minutes.
9. The method of claim 1, further comprising contacting at least a
portion of the substrate surface with a conversion composition
comprising a lanthanide series metal cation, a Group IIIB metal
cation, a Group IVB metal cation, or combinations thereof; wherein
the contacting with the conversion composition occurs prior to
and/or following the contacting with the sealing composition.
10. The method of claim 9, wherein the conversion composition is
applied to provide a film on the substrate resulting in a level of
the lanthanide metal, Group IIIB metal cation, and/or Group IV
metal cation on the treated substrate surface of at least 100
counts greater than on a surface of a substrate that does not have
the film thereon as measured by X-ray fluorescence (measured using
X-Met 7500, Oxford Instruments; operating parameters 60 second
timed assay, 15 Kv, 45 .mu.A, filter 3, T(p)=1.5 .mu.s for
lanthanides, Group IIIB metals, and Group IVB metals except
zirconium; operating parameters 60 second timed assay, 40 Kv, 10
.mu.A, filter 4, T(p)=1.5 .mu.s for zirconium).
11. The method of claim 1, wherein the substrate comprises
aluminum, aluminum alloys, or combinations thereof.
12. The method of claim 9, further comprising heating the substrate
for 15 minutes to 30 minutes at a temperature of 110.degree. C. to
232.degree. C.
13. A substrate treated with the method of claim 1.
14. A system for treating a substrate comprising: a conversion
composition for treating at a least a portion of the substrate, the
conversion composition comprising a lanthanide series metal cation,
a Group IIIB metal cation, a Group IVB metal cation, or a
combination thereof; and a sealing composition for treating at
least a portion of the substrate, the sealing composition
comprising a lithium cation.
15. The system of claim 14, wherein the lanthanide series metal
cation, Group IIIB metal cation and/or Group IVB metal cation
comprises cerium, praseodymium, yttrium, zirconium, titanium, or
combinations thereof.
16. The system of claim 14, wherein the lanthanide series metal
cation, Group IIIB metal cation and/or the Group IVB metal cation
is present in an amount of 50 ppm to 500 ppm, based on a total
weight of the conversion composition.
17. The system of claim 14, wherein the lithium cation is present
in the sealing composition in an amount of 5 ppm to 30,000 ppm (as
lithium cation) based on a total weight of the sealing
composition.
18. The system of claim 14, wherein the sealing composition has a
pH of 9.5 to 12.5.
19. The system of claim 14, further comprising an alkaline cleaning
composition comprising an azole.
20. A substrate treated with the system of claim 14.
21. The substrate of claim 20, wherein the substrate has at least a
50% reduction in the number of pits on the substrate surface
compared to a substrate not treated with the sealing composition
following 3 day exposure in neutral salt spray cabinet operated
according to ASTM B117.
22. The substrate of claim 20, wherein the substrate has at least a
50% reduction in the number of pits on the substrate surface
compared to a substrate treated with the conversion composition or
the sealing composition but not the conversion composition and the
sealing composition following 7 day exposure in neutral salt spray
cabinet operated according to ASTM B117.
23. The substrate of claim 20, further comprising a primer layer,
an electrocoat layer, and/or a topcoat layer.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to U.S. Provisional
Application No. 62/374,188, filed on Aug. 12, 2016 and entitled
"Sealing Composition" and to U.S. Provisional Application No.
62/374,199, filed Aug. 12, 2016 and entitled "Pretreatment
Composition", both of which are incorporated in their entirety
herein by reference.
FIELD
[0002] The present invention relates to sealing compositions and
methods for treating a metal substrate. The present invention also
relates to a coated metal substrate.
BACKGROUND
[0003] The oxidation and degradation of metals used in aerospace,
commercial, and private industries are a serious and costly
problem. To prevent the oxidation and degradation of the metals
used in these applications, an inorganic protective coating can be
applied to the metal surface. This inorganic protective coating,
also referred to as a conversion coating, may be the only coating
applied to the metal, or the coating can be an intermediate coating
to which subsequent coatings are applied.
[0004] Chromate based coatings are currently used as inorganic
conversion coatings because they provide corrosion resistant
properties and adhesion for application of subsequent coatings.
However, due to environmental concerns over chromium based
compounds in the environment, there is a need for an
environmentally safer replacement for chromate based conversion
coatings. There is also a need for environmentally safer conversion
coatings that can provide corrosion resistance to an underlying
metal surface and adhesion to subsequently applied coatings.
[0005] Cerium and other rare earth element containing coatings have
been identified as potential replacements for chromate based
coatings in metal finishing. These coatings include cerium and
other rare earth element containing coatings that are formed by
various processes such as immersion, electroplating from a cerium
nitrate solution, plating from an acidic cerium chloride containing
solution and an oxidant (at elevated temperatures), as well as
multi-step processes, and electrolytic and non-electrolytic
processes having a sealing step.
[0006] However, at least some of the coatings prepared using these
compositions and methods do not perform as well as those formed
using chromate treatments and/or can develop corrosion and/or pits
on the surface. Further, at least some of the cerium and other rare
earth element-containing coatings known in the art can also suffer
from one or more of the following disadvantages: (1) a tendency of
the rare earth element to precipitate in solution away from the
metal surface in the form of a sludge-like material; (2) difficulty
in obtaining a uniform coating which does not tend to over-coat and
exhibit poor adhesion to the substrate; (3) the necessity to use
multiple steps and extensive periods of time to deposit a coating;
and (4) the necessity to use specific conversions and solution
compositions in order to coat multiply alloys, especially aluminum
2024 alloys.
[0007] Therefore, there is a need for a method of treating a
substrate that can replace chromate based conversion coatings and
that overcomes several of the deficiencies, disadvantages and
undesired parameters of known replacements for chromate based
conversion coatings.
SUMMARY
[0008] Disclosed herein is a method of treating a substrate
comprising: contacting at least a portion of the substrate surface
with a sealing composition comprising a lithium cation. According
to the present invention, the method may further comprise
contacting at least a portion of the substrate with a lanthanide
series metal cation, a Group IIIB metal cation, a Group IVB metal
cation, or a combination thereof. According to the invention, the
sealing composition may be applied to provide a layer of the dried
sealing composition having a thickness of 5 nm to 550 nm.
[0009] Also disclosed is a system for treating a substrate
comprising: a conversion composition for treating at a least a
portion of the substrate, the conversion composition comprising a
lanthanide series metal cation, a Group IIIB metal cation, a Group
IVB metal cation, or a combination thereof; and a sealing
composition for treating at least a portion of the substrate, the
sealing composition comprising a lithium cation.
[0010] Also disclosed are substrates obtainable by the system
and/or methods.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 shows a schematic illustrating thickness of a layer
of the sealing composition on a substrate surface.
DETAILED DESCRIPTION
[0012] Disclosed herein according to the invention is a system for
treating a substrate comprising, or in some instances, consisting
essentially of, or in some instances, consisting of, a sealing
composition comprising, or in instances, consisting essentially of,
or in some instances, consisting of, a lithium cation. The system
may further comprise, or in some instances consist essentially of,
or in some instances, consist of, a conversion composition
comprising, or in some instances, consisting essentially of, or in
some instances, consisting of, a lanthanide series metal cation, a
Group IIIB metal cation, a Group IVB metal cation, or a combination
thereof. In some instances, the system may further comprise, or
consist essentially of, or consist of, a cleaning composition
and/or a deoxidizer.
[0013] As mentioned above, also disclosed herein is a method of
treating a substrate comprising, or in some instances, consisting
essentially of, or in some instances, consisting of: contacting at
least a portion of the substrate surface with a sealing composition
comprising, or in some instances, consisting essentially of, or in
some instances, consisting of, a lithium cation. According to the
invention, the method may also comprise, or in some instances,
consist essentially of, or in some instances, consist of,
contacting at least a portion of the substrate surface with a
conversion composition comprising, or in some instances, consisting
essentially of, or in some instances, consisting of, a lanthanide
series metal cation, a Group IIIB metal cation, a Group IVB metal
cation, or a combination thereof.
[0014] As described herein, a substrate treated with the system
and/or method of the present invention may comprise, or in some
instances consist essentially of, or in some instances, consist of,
a layer formed from the sealing composition comprising a lithium
cation. In some instances, the substrate may further comprise a
film or a layer formed from the conversion composition comprising
cations of a lanthanide series metal, a Group IIIB metal, and/or a
Group IVB metal.
[0015] Suitable substrates that may be used in the present
invention include metal substrates, metal alloy substrates, and/or
substrates that have been metallized, such as nickel plated
plastic. According to the present invention, the metal or metal
alloy can comprise or be steel, aluminum, zinc, nickel, and/or
magnesium. For example, the steel substrate could be cold rolled
steel, hot rolled steel, electrogalvanized steel, and/or hot dipped
galvanized steel. Aluminum alloys of the 1XXX, 2XXX, 3XXX, 4XXX,
5XXX, 6XXX, or 7XXX series as well as clad aluminum alloys also may
be used as the substrate. Aluminum alloys may comprise 0.01% by
weight copper to 10% by weight copper. Aluminum alloys which are
treated may also include castings, such as 1XX.X, 2XX.X, 3XX.X,
4XX.X, 5XX.X, 6XX.X, 7XX.X, 8XX.X, or 9XX.X (e.g.: A356.0).
Magnesium alloys of the AZ31B, AZ91C, AM60B, or EV31A series also
may be used as the substrate. The substrate used in the present
invention may also comprise titanium and/or titanium alloys, zinc
and/or zinc alloys, and/or nickel and/or nickel alloys. According
to the present invention, the substrate may comprise a portion of a
vehicle such as a vehicular body (e.g., without limitation, door,
body panel, trunk deck lid, roof panel, hood, roof and/or
stringers, rivets, landing gear components, and/or skins used on an
aircraft) and/or a vehicular frame. As used herein, "vehicle" or
variations thereof includes, but is not limited to, civilian,
commercial and military aircraft, and/or land vehicles such as
cars, motorcycles, and/or trucks.
[0016] The sealing composition may comprise a lithium cation. The
lithium cation may be in the form of a lithium salt. In addition,
the sealing composition also may further comprise at least one
Group IA metal cation other than lithium, a Group VB metal cation,
and/or Group VIB metal cation. The at least one Group IA metal
cation other than lithium, a Group VB metal cation, and/or Group
VIB metal cation may be in the form of a salt. Nonlimiting examples
of anions suitable for forming a salt with the lithium, Group IA
cations other than lithium, Group VB cations, and/or Group VIB
cations include carbonates, hydroxides, nitrates, halogens,
sulfates, phosphates and silicates (e.g., orthosilicates and
metasilicates) such that the metal salt may comprise a carbonate,
an hydroxide, a nitrate, a halide, a sulfate, a phosphate, a
silicate (e.g., orthosilicate or metasilicate), a permanganate, a
chromate, a vanadate, a molybdate, and/or a perchlorate.
[0017] According to the present invention, the metal salts of the
sealing composition (i.e., the salts of lithium, Group IA metals
other than lithium, Group VB, and/or Group VIB) each may be present
in the sealing composition in an amount of at least 25 ppm, such as
at least 150 ppm, such as at least 500 ppm (calculated as total
compound) based on total weight of the sealing composition, and in
some instances, no more than 30000 ppm, such as no more than 2000
ppm, such as no more than 1500 ppm (calculated as total compound)
based on total weight of the sealing composition. According to the
present invention, the metal salts of the sealing composition
(i.e., the salts of lithium, Group IA metals other than lithium,
Group VB, and/or Group VIB) each may be present in the sealing
composition in an amount of 25 ppm to 30000 ppm, such as 150 ppm to
2000 ppm, such as 500 ppm to 1500 (calculated as total compound)
based on total weight of the sealing composition.
[0018] According to the present invention, the lithium cation, the
Group IA cation other than lithium, the Group VB metal cation, and
the Group VIB metal cation each may be present in the sealing
composition in an amount of at least 5 ppm, such as at least 50
ppm, such as at least 150 ppm, such as at least 250 ppm (calculated
as cation) based on total weight of the sealing composition, and in
some instances, may be present in an amount of no more than 5500
ppm, such as no more than 1200 ppm, such as no more than 1000 ppm,
such as no more than 500 ppm, (calculated as cation) based on total
weight of the sealing composition. In some instances, according to
the present invention, the lithium cation, the Group IA cation
other than lithium, the Group VB metal cation, and the Group VIB
metal cation each may be present in the sealing composition in an
amount of 5 ppm to 5500 ppm, such as 50 ppm to 1000 ppm,
(calculated as cation) based on total weight of the sealing
composition, such as 150 ppm to 500 ppm.
[0019] According to the present invention, the lithium salt of the
present invention may comprise an inorganic lithium salt, an
organic lithium salt, or combinations thereof. According to the
present invention, the anion and the cation of the lithium salt
both may be soluble in water. According to the present invention,
for example, the lithium salt may have a solubility constant in
water at a temperature of 25.degree. C. (K; 25.degree. C.) of at
least 1.times.10.sup.-11, such as least 1.times.10.sup.-4, and in
some instances, may be no more than 5.times.10.sup.+2. According to
the present invention, the lithium salt may have a solubility
constant in water at a temperature of 25.degree. C. (K; 25.degree.
C.) of 1.times.10.sup.-11 to 5.times.10.sup.+2, such as
1.times.10.sup.-4 to 5.times.10.sup.+2. As used herein, "solubility
constant" means the product of the equilibrium concentrations of
the ions in a saturated aqueous solution of the respective lithium
salt. Each concentration is raised to the power of the respective
coefficient of ion in the balanced equation. The solubility
constants for various salts can be found in the Handbook of
Chemistry and Physics.
[0020] According to the present invention, the sealing composition
of the present invention may an include oxidizing agent, such as
hydrogen peroxide, persulfates, perchlorates, sparged oxygen,
bromates, peroxi-benzoates, ozone, and the like, or combinations
thereof. For example, the sealing composition may comprise 0.1 wt %
to 15 wt % of an oxidizing agent based on total weight of the
sealing composition, such as 2 wt % to 10 wt %, such as 6 wt % to 8
wt %. Alternatively, according to the present invention, the
sealing composition may be substantially free, or in some cases,
essentially free, or in some cases, completely free, of an
oxidizing agent.
[0021] According to the present invention, the sealing composition
may exclude Group IIA metal cations or Group IIA metal-containing
compounds, including but not limited to calcium. Non-limiting
examples of such materials include Group IIA metal hydroxides,
Group IIA metal nitrates, Group IIA metal halides, Group IIA metal
sulfamates, Group IIA metal sulfates, Group IIA carbonates and/or
Group IIA metal carboxylates. When a sealing composition and/or a
coating or a layer, respectively, formed from the same is
substantially free, essentially free, or completely free of a Group
IIA metal cation, this includes Group IIA metal cations in any
form, such as, but not limited to, the Group IIA metal-containing
compounds listed above.
[0022] According to the present invention, the sealing composition
may exclude chromium or chromium-containing compounds. As used
herein, the term "chromium-containing compound" refers to materials
that include hexavalent chromium. Non-limiting examples of such
materials include chromic acid, chromium trioxide, chromic acid
anhydride, dichromate salts, such as ammonium dichromate, sodium
dichromate, potassium dichromate, and calcium, barium, magnesium,
zinc, cadmium, and strontium dichromate. When a sealing composition
and/or a coating or a layer, respectively, formed from the same is
substantially free, essentially free, or completely free of
chromium, this includes chromium in any form, such as, but not
limited to, the hexavalent chromium-containing compounds listed
above.
[0023] Thus, optionally, according to the present invention, the
present sealing compositions and/or coatings or layers,
respectively, deposited from the same may be substantially free,
may be essentially free, and/or may be completely free of one or
more of any of the elements or compounds listed in the preceding
paragraph. A sealing composition and/or coating or layer,
respectively, formed from the same that is substantially free of
chromium or derivatives thereof means that chromium or derivatives
thereof are not intentionally added, but may be present in trace
amounts, such as because of impurities or unavoidable contamination
from the environment. In other words, the amount of material is so
small that it does not affect the properties of the sealing
composition; in the case of chromium, this may further include that
the element or compounds thereof are not present in the sealing
compositions and/or coatings or layers, respectively, formed from
the same in such a level that it causes a burden on the
environment. The term "substantially free" means that the sealing
compositions and/or coating or layers, respectively, formed from
the same contain less than 10 ppm of any or all of the elements or
compounds listed in the preceding paragraph, based on total weight
of the composition or the layer, respectively, if any at all. The
term "essentially free" means that the sealing compositions and/or
coatings or layers, respectively, formed from the same contain less
than 1 ppm of any or all of the elements or compounds listed in the
preceding paragraph, if any at all. The term "completely free"
means that the sealing compositions and/or coatings or layers,
respectively, formed from the same contain less than 1 ppb of any
or all of the elements or compounds listed in the preceding
paragraph, if any at all.
[0024] According to the present invention, the sealing composition
may, in some instances, exclude phosphate ions or
phosphate-containing compounds and/or the formation of sludge, such
as aluminum phosphate, iron phosphate, and/or zinc phosphate,
formed in the case of using a treating agent based on zinc
phosphate. As used herein, "phosphate-containing compounds" include
compounds containing the element phosphorous such as ortho
phosphate, pyrophosphate, metaphosphate, tripolyphosphate,
organophosphonates, and the like, and can include, but are not
limited to, monovalent, divalent, or trivalent cations such as:
sodium, potassium, calcium, zinc, nickel, manganese, aluminum
and/or iron. When a composition and/or a layer or coating
comprising the same is substantially free, essentially free, or
completely free of phosphate, this includes phosphate ions or
compounds containing phosphate in any form.
[0025] Thus, according to the present invention, sealing
composition and/or layers deposited from the same may be
substantially free, or in some cases may be essentially free, or in
some cases may be completely free, of one or more of any of the
ions or compounds listed in the preceding paragraph. A sealing
composition and/or layers deposited from the same that is
substantially free of phosphate means that phosphate ions or
compounds containing phosphate are not intentionally added, but may
be present in trace amounts, such as because of impurities or
unavoidable contamination from the environment. In other words, the
amount of material is so small that it does not affect the
properties of the composition; this may further include that
phosphate is not present in the sealing compositions and/or layers
deposited from the same in such a level that they cause a burden on
the environment. The term "substantially free" means that the
sealing compositions and/or layers deposited from the same contain
less than 5 ppm of any or all of the phosphate anions or compounds
listed in the preceding paragraph, based on total weight of the
composition or the layer, respectively, if any at all. The term
"essentially free" means that the sealing compositions and/or
layers comprising the same contain less than 1 ppm of any or all of
the phosphate anions or compounds listed in the preceding
paragraph. The term "completely free" means that the sealing
compositions and/or layers comprising the same contain less than 1
ppb of any or all of the phosphate anions or compounds listed in
the preceding paragraph, if any at all.
[0026] According to the present invention, the sealing composition
may, in some instances, exclude fluoride or fluoride sources. As
used herein, "fluoride sources" include monofluorides, bifluorides,
fluoride complexes, and mixtures thereof known to generate fluoride
ions. When a composition and/or a layer or coating comprising the
same is substantially free, essentially free, or completely free of
fluoride, this includes fluoride ions or fluoride sources in any
form, but does not include unintentional fluoride that may be
present in a bath as a result of, for example, carry-over from
prior treatment baths in the processing line, municipal water
sources (e.g.: fluoride added to water supplies to prevent tooth
decay), fluoride from a pretreated substrate, or the like. That is,
a bath that is substantially free, essentially free, or completely
free of fluoride, may have unintentional fluoride that may be
derived from these external sources, even though the composition
used to make the bath prior to use on the processing line was
substantially free, essentially free, or completely free of
fluoride.
[0027] For example, the sealing composition may be substantially
free of any fluoride-sources, such as ammonium and alkali metal
fluorides, acid fluorides, fluoroboric, fluorosilicic,
fluorotitanic, and fluorozirconic acids and their ammonium and
alkali metal salts, and other inorganic fluorides, nonexclusive
examples of which are: zinc fluoride, zinc aluminum fluoride,
titanium fluoride, zirconium fluoride, nickel fluoride, ammonium
fluoride, sodium fluoride, potassium fluoride, and hydrofluoric
acid, as well as other similar materials known to those skilled in
the art.
[0028] Fluoride present in the sealing composition that is not
bound to metals ions such as Group IVB metal ions, or hydrogen ion,
defined herein as "free fluoride," may be measured as an
operational parameter in the sealing composition bath using, for
example, an Orion Dual Star Dual Channel Benchtop Meter equipped
with a fluoride ion selective electrode ("ISE") available from
Thermoscientific, the Symphony.RTM. Fluoride Ion Selective
Combination Electrode supplied by VWR International, or similar
electrodes. See, e.g., Light and Cappuccino, Determination of
fluoride in toothpaste using an ion-selective electrode, J. Chem.
Educ., 52:4, 247-250, April 1975. The fluoride ISE may be
standardized by immersing the electrode into solutions of known
fluoride concentration and recording the reading in millivolts, and
then plotting these millivolt readings in a logarithmic graph. The
millivolt reading of an unknown sample can then be compared to this
calibration graph and the concentration of fluoride determined.
Alternatively, the fluoride ISE can be used with a meter that will
perform the calibration calculations internally and thus, after
calibration, the concentration of the unknown sample can be read
directly.
[0029] Fluoride ion is a small negative ion with a high charge
density, so in aqueous solution it is frequently complexed with
metal ions having a high positive charge density, such as Group IVB
metal ions, or with hydrogen ion. Fluoride anions in solution that
are ionically or covalently bound to metal cations or hydrogen ion
are defined herein as "bound fluoride." The fluoride ions thus
complexed are not measurable with the fluoride ISE unless the
solution they are present in is mixed with an ionic strength
adjustment buffer (e.g.: citrate anion or EDTA) that releases the
fluoride ions from such complexes. At that point (all of) the
fluoride ions are measurable by the fluoride ISE, and the
measurement is known as "total fluoride". Alternatively, the total
fluoride can be calculated by comparing the weight of the fluoride
supplied in the sealer composition by the total weight of the
composition.
[0030] According to the present invention, the treatment
composition may, in some instances, be substantially free, or in
some instances, essentially free, or in some instances, completely
free, of cobalt ions or cobalt-containing compounds. As used
herein, "cobalt-containing compounds" include compounds, complexes
or salts containing the element cobalt such as, for example, cobalt
sulfate, cobalt nitrate, cobalt carbonate and cobalt acetate. When
a composition and/or a layer or coating comprising the same is
substantially free, essentially free, or completely free of cobalt,
this includes cobalt ions or compounds containing cobalt in any
form.
[0031] According to the present invention, the treatment
composition may, in some instances, be substantially free, or in
some instances, essentially free, or in some instances, completely
free, of vanadium ions or vanadium-containing compounds. As used
herein, "vanadium-containing compounds" include compounds,
complexes or salts containing the element vanadium such as, for
example, vanadates and decavanadates that include counterions of
alkali metal or ammonium cations, including, for example, sodium
ammonium decavanadate. When a composition and/or a layer or coating
comprising the same is substantially free, essentially free, or
completely free of vanadium, this includes vanadium ions or
compounds containing vanadium in any form.
[0032] According to the present invention, the sealing composition
may optionally further contain an indicator compound, so named
because it indicates, for example, the presence of a chemical
species, such as a metal ion, the pH of a composition, and the
like. An "indicator", "indicator compound", and like terms as used
herein refer to a compound that changes color in response to some
external stimulus, parameter, or condition, such as the presence of
a metal ion, or in response to a specific pH or range of pHs.
[0033] The indicator compound used according to the present
invention can be any indicator known in the art that indicates the
presence of a species, a particular pH, and the like. For example,
a suitable indicator may be one that changes color after forming a
metal ion complex with a particular metal ion. The metal ion
indicator is generally a highly conjugated organic compound. A
"conjugated compound" as used herein, and as will be understood by
those skilled in the art, refers to a compound having two double
bonds separated by a single bond, for example two carbon-carbon
double bonds with a single carbon-carbon bond between them. Any
conjugated compound can be used according to the present
invention.
[0034] Similarly, the indicator compound can be one in which the
color changes upon change of the pH; for example, the compound may
be one color at an acidic or neutral pH and change color in an
alkaline pH, or vice versa. Such indicators are well known and
widely commercially available. An indicator that "changes color
upon transition from a first pH to a second pH" (i.e., from a first
pH to a second pH that is more or less acidic or alkaline)
therefore has a first color (or is colorless) when exposed to a
first pH and changes to a second color (or goes from colorless to
colored) upon transition to a second pH (i.e., one that is either
more or less acidic or alkaline than the first pH). For example, an
indicator that "changes color upon transition to a more alkaline pH
(or less acidic pH) goes from a first color/colorless to a second
color/color when the pH transitions from acidic/neutral to
alkaline. For example, an indicator that "changes color upon
transition to a more acidic pH (or less alkaline pH) goes from a
first color/colorless to a second color/color when the pH
transitions from alkaline/neutral to acidic.
[0035] Non-limiting examples of such indicator compounds include
methyl orange, xylenol orange, catechol violet, bromophenol blue,
green and purple, eriochrome black T, Celestine blue, hematoxylin,
calmagite, gallocyanine, and combinations thereof. Optionally, the
indicator compound may comprise an organic indicator compound that
is a metal ion indicator. Nonlimiting examples of indicator
compounds include those found in Table 1. Fluorescent indicators,
which will emit light in certain conditions, can also be used
according to the present invention, although the use of a
fluorescent indicator also may be specifically excluded. That is,
alternatively, conjugated compounds that exhibit fluorescence are
specifically excluded. As used herein, "fluorescent indicator" and
like terms refer to compounds, molecules, pigments, and/or dyes
that will fluoresce or otherwise exhibit color upon exposure to
ultraviolet or visible light. To "fluoresce" will be understood as
emitting light following absorption of shorter wavelength light or
other electromagnetic radiation. Examples of such indicators, often
referred to as "tags," include acridine, anthraquinone, coumarin,
diphenylmethane, diphenylnaphthlymethane, quinoline, stilbene,
triphenylmethane, anthracine and/or molecules containing any of
these moieties and/or derivatives of any of these such as
rhodamines, phenanthridines, oxazines, fluorones, cyanines and/or
acridines.
TABLE-US-00001 TABLE 1 Compound Structure CAS Reg. No. Catechol
Violet Synonyms: Catecholsulfonphthalein;
Pyrocatecholsulfonephthalein; Pyrocatechol Violet ##STR00001##
115-41-3 Xylenol Orange Synonym: 3,3'-Bis[N,N-
bis(carboxymethyl)aminomethyl]- o-cresolsulfonephthalein
tetrasodium salt ##STR00002## 3618-43-7
[0036] According to the present invention, the conjugated compound
useful as indicator may for example comprise catechol violet, as
shown in Table 1. Catechol violet (CV) is a sulfone phthalein dye
made from condensing two moles of pyrocatechol with one mole of
o-sulfobenzoic acid anhydride. It has been found that CV has
indicator properties and when incorporated into compositions having
metal ions, it forms complexes, making it useful as a
complexiometric reagent. As the composition containing the CV
chelates metal ions coming from the metal substrate (i.e., those
having bi- or higher valence), a generally blue to blue-violet
color is observed.
[0037] 1 Xylenol orange, as shown in Table 1 may likewise be
employed in the compositions according to the present invention. It
has been found that xylenol orange has metal ion (i.e., those
having bi- or higher valence) indicator properties and when
incorporated into compositions having metal ions, it forms
complexes, making it useful as a complexiometric reagent. As the
composition containing the xylenol orange chelates metal ions, a
solution of xylenol orange turns from red to a generally blue
color.
[0038] According to the present invention, the indicator compound
may be present in the sealing composition in an amount of at least
0.01 g/1000 g sealing composition, such as at least 0.05 g/1000 g
sealing composition, and in some instances, no more than 3 g/1000 g
sealing composition, such as no more than 0.3 g/1000 g sealing
composition. According to the present invention, the indicator
compound may be present in the sealing composition in an amount of
0.01 g/1000 g sealing composition to 3 g/1000 g sealing
composition, such as 0.05 g/1000 g sealing composition to 0.3
g/1000 g sealing composition.
[0039] According to the present invention, the indicator compound
changing color in response to a certain external stimulus provides
a benefit when using the sealing composition in that it can serve,
for example, as a visual indication that a substrate has been
treated with the composition. For example, a sealing composition
comprising an indicator that changes color when exposed to a metal
ion that is present in the substrate will change color upon
complexing with metal ions in that substrate; this allows the user
to see that the substrate has been contacted with the composition.
Similar benefits can be realized by depositing an alkaline or acid
layer on a substrate and contacting the substrate with a
composition of the present invention that changes color when
exposed to an alkaline or acidic pH.
[0040] Optionally, the sealing composition of the present invention
may further comprise a nitrogen-containing heterocyclic compound.
The nitrogen-containing heterocyclic compound may include cyclic
compounds having 1 nitrogen atom, such as pyrroles, and azole
compounds having 2 or more nitrogen atoms, such as pyrazoles,
imidazoles, triazoles, tetrazoles and pentazoles, 1 nitrogen atom
and 1 oxygen atom, such as oxazoles and isoxazoles, or 1 nitrogen
atom and 1 sulfur atom, such as thiazoles and isothiazoles.
Nonlimiting examples of suitable azole compounds include
2,5-dimercapto-1,3,4-thiadiazole (CAS: 1072-71-5), 1H-benzotriazole
(CAS: 95-14-7), 1H-1,2,3-triazole (CAS: 288-36-8),
2-amino-5-mercapto-1,3,4-thiadiazole (CAS: 2349-67-9), also named
5-amino-1,3,4-thiadiazole-2-thiol, and 2-amino-1,3,4-thiadiazole
(CAS: 4005-51-0). In some embodiments, for example, the azole
compound comprises 2,5-dimercapto-1,3,4-thiadiazole. Additionally,
according to the present invention, the nitrogen-containing
heterocyclic compound may be in the form of a salt, such as a
sodium salt.
[0041] The nitrogen-containing heterocyclic compound may be present
in the sealing composition at a concentration of at least 0.0005 g
per liter of composition, such as at least 0.0008 g per liter of
composition, such as at least 0.002 g per liter of composition, and
in some instances, may be present in the sealing composition in an
amount of no more than 3 g per liter of composition, such as no
more than 0.2 g per liter of composition, such as no more than 0.1
g per liter of composition. According to the present invention, the
nitrogen-containing heterocyclic compound may be present in the
sealing composition (if at all) at a concentration of 0.0005 g per
liter of composition to 3 g per liter of composition, such as
0.0008 g per liter of composition to 0.2 g per liter of
composition, such as 0.002 g per liter of composition to 0.1 g per
liter of composition.
[0042] According to the present invention, the sealing composition
may comprise an aqueous medium and optionally may contain other
materials such as at least one organic solvent. Nonlimiting
examples of suitable such solvents include propylene glycol,
ethylene glycol, glycerol, low molecular weight alcohols, and the
like. When present, if at all, the organic solvent may be present
in the sealing composition in an amount of at least 1 g solvent per
liter of sealing composition, such as at least about 2 g solvent
per liter of sealing solution, and in some instances, may be
present in an amount of no more than 40 g solvent per liter of
sealing composition, such as no more than 20 g solvent per liter of
sealing solution. According to the present invention, the organic
solvent may be present in the sealing composition, if at all, in an
amount of 1 g solvent per liter of sealing composition to 40 g
solvent per liter of sealing composition, such as 2 g solvent per
liter of sealing composition to 20 g solvent per liter of sealing
composition.
[0043] According to the present invention, the pH of the sealing
composition may be at least 9.5, such as at least 10, such as at
least 11, and in some instances may be no higher than 12.5, such as
no higher than 12, such as no higher than 11.5. According to the
present invention, the pH of the sealing composition may be 9.5 to
12.5, such as 10 to 12, such as 11 to 11.5. The pH of the sealing
composition may be adjusted using, for example, any acid and/or
base as is necessary. According to the present invention, the pH of
the sealing composition may be maintained through the inclusion of
an acidic material, including carbon dioxide, water soluble and/or
water dispersible acids, such as nitric acid, sulfuric acid, and/or
phosphoric acid. According to the present invention, the pH of the
sealing composition may be maintained through the inclusion of a
basic material, including water soluble and/or water dispersible
bases, including carbonates such as Group I carbonates, Group II
carbonates, hydroxides such as sodium hydroxide, potassium
hydroxide, or ammonium hydroxide, ammonia, and/or amines such as
triethylamine, methylethyl amine, or mixtures thereof.
[0044] As mentioned above, the sealing composition may comprise a
carrier, often an aqueous medium, so that the composition is in the
form of a solution or dispersion of the lithium cation in the
carrier. According to the present invention, the solution or
dispersion may be brought into contact with the substrate by any of
a variety of known techniques, such as dipping or immersion,
spraying, intermittent spraying, dipping followed by spraying,
spraying followed by dipping, brushing, or roll-coating. According
to the invention, the solution or dispersion when applied to the
metal substrate may be at a temperature ranging from 40.degree. F.
to about 160.degree. F., such as 60.degree. F. to 110.degree. F.
For example, the process of contacting the metal substrate with the
sealing composition may be carried out at ambient or room
temperature. The contact time is often from about 1 second to about
15 minutes, such as about 5 seconds to about 2 minutes.
[0045] According to the present invention, following the contacting
with the sealing composition, the substrate optionally may be air
dried at room temperature or may be dried with hot air, for
example, by using an air knife, by flashing off the water by brief
exposure of the substrate to a high temperature, such as by drying
the substrate in an oven at 15.degree. C. to 100.degree. C., such
as 20.degree. C. to 90.degree. C., or in a heater assembly using,
for example, infrared heat, such as for 10 minutes at 70.degree.
C., or by passing the substrate between squeegee rolls. According
to the present invention, the substrate surface may be partially,
or in some instances, completely dried prior to any subsequent
contact of the substrate surface with any water, solutions,
compositions, or the like. As used herein with respect to a
substrate surface, "completely dry" or "completely dried" means
there is no moisture on the substrate surface visible to the human
eye.
[0046] Optionally, according to the present invention, following
the contacting with the sealing composition, the substrate
optionally is not rinsed or contacted with any aqueous solutions
prior to contacting at least a portion of the substrate surface
with subsequent treatment compositions to form films, layers,
and/or coatings thereon (described below).
[0047] Optionally, according to the present invention, following
the contacting with the sealing composition, the substrate
optionally may be contacted with tap water, deionized water, RO
water and/or any aqueous solution known to those of skill in the
art of substrate treatment, wherein such water or aqueous solution
may be at a temperature of room temperature (60.degree. F.) to
212.degree. F. The substrate then optionally may be dried, for
example air dried or dried with hot air as described in the
preceding paragraph such that the substrate surface may be
partially, or in some instances, completely dried prior to any
subsequent contact of the substrate surface with any water,
solutions, compositions, or the like.
[0048] According to the present invention, the thickness of the
layer formed by the treatment composition may for instance be up to
550 nm, such as 5 nm to 550 nm, such as 10 nm to 400 nm, such as 25
nm to 250 nm. Thickness of layer formed from the treatment
composition can be determined using a handful of analytical
techniques including, but not limited to XPS (x-ray photoelectron
spectroscopy) depth profiling or TEM (transmission electron
microscopy). As used herein, "thickness," when used with respect to
a layer formed by the treatment composition of the present
invention, refers to either (a) a layer formed above the original
air/substrate interface, (b) a modified layer formed below the
pretreatment/substrate interface, or (c) a combination of (a) and
(b), as illustrated in FIG. 1. Although modified layer (b) is shown
extending to the pretreatment/substrate interface in FIG. 1, an
intervening layer may be present between the modified layer (b) and
the pretreatment/substrate interface. Likewise, (c), a combination
of (a) and (b), is not limited to a continuous layer and may
include multiple layers with intervening layers therebetween, and
the measurement of the thickness of layer (c) may exclude the
intervening layers.
[0049] According to the present invention, the substrate having the
layer formed from the sealing composition may have at least a 50%
reduction in the number of pits on the substrate surface compared
to a substrate that does not have a layer formed from the sealing
composition thereon following 3 day exposure in neutral salt spray
cabinet operated according to ASTM B117.
[0050] Additionally, according to the present invention, the
substrate having the layer formed from the sealing composition may
have at least a 50% reduction in the number of pits on the
substrate surface compared to a substrate that does not have a
layer formed from the sealing composition thereon following 7 day
exposure in neutral salt spray cabinet operated according to ASTM
B117.
[0051] According to the present invention, at least a portion of
the substrate surface may be cleaned and/or deoxidized prior to
contacting at least a portion of the substrate surface with a
sealing composition described above, in order to remove grease,
dirt, and/or other extraneous matter. At least a portion of the
surface of the substrate may be cleaned by physical and/or chemical
means, such as mechanically abrading the surface and/or
cleaning/degreasing the surface with commercially available
alkaline or acidic cleaning agents that are well known to those
skilled in the art. Examples of alkaline cleaners suitable for use
in the present invention include Chemkleen.TM. 166HP, 166M/C, 177,
490MX, 2010LP, and Surface Prep 1 (SPI), Ultrax 32, Ultrax 97,
Ultrax 29, and Ultrax92D, each of which are commercially available
from PPG Industries, Inc. (Cleveland, Ohio), and any of the DFM
Series, RECC 1001, and 88X1002 cleaners commercially available from
PRC-DeSoto International, Sylmar, Calif.), and Turco 4215-NCLT and
Ridolene (commercially available from Henkel Technologies, Madison
Heights, Mich.). Such cleaners are often preceded or followed by a
water rinse, such as with tap water, distilled water, or
combinations thereof.
[0052] As mentioned above, according to the present invention, at
least a portion of the cleaned substrate surface may be deoxidized,
mechanically and/or chemically. As used herein, the term
"deoxidize" means removal of the oxide layer found on the surface
of the substrate in order to promote uniform deposition of the
conversion composition (described below), as well as to promote the
adhesion of the conversion composition coating to the substrate
surface. Suitable deoxidizers will be familiar to those skilled in
the art. A typical mechanical deoxidizer may be uniform roughening
of the substrate surface, such as by using a scouring or cleaning
pad. Typical chemical deoxidizers include, for example, acid-based
deoxidizers such as phosphoric acid, nitric acid, fluoroboric acid,
sulfuric acid, chromic acid, hydrofluoric acid, and ammonium
bifluoride, or Amchem 7/17 deoxidizers (available from Henkel
Technologies, Madison Heights, Mich.), OAKITE DEOXIDIZER LNC
(commercially available from Chemetall), TURCO DEOXIDIZER 6
(commercially available from Henkel), or combinations thereof.
Often, the chemical deoxidizer comprises a carrier, often an
aqueous medium, so that the deoxidizer may be in the form of a
solution or dispersion in the carrier, in which case the solution
or dispersion may be brought into contact with the substrate by any
of a variety of known techniques, such as dipping or immersion,
spraying, intermittent spraying, dipping followed by spraying,
spraying followed by dipping, brushing, or roll-coating. According
to the present invention, the skilled artisan will select a
temperature range of the solution or dispersion, when applied to
the metal substrate, based on etch rates, for example, at a
temperature ranging from 50.degree. F. to 150.degree. F.
(10.degree. C. to 66.degree. C.), such as from 70.degree. F. to
130.degree. F. (21.degree. C. to 54.degree. C.), such as from
80.degree. F. to 120.degree. F. (27.degree. C. to 49.degree. C.).
The contact time may be from 30 seconds to 20 minutes, such as 1
minute to 15 minutes, such as 90 seconds to 12 minutes, such as 3
minutes to 9 minutes.
[0053] Following the cleaning and/or deoxidizing step(s), the
substrate optionally may be rinsed with tap water, deionized water,
and/or an aqueous solution of rinsing agents in order to remove any
residue. According to the present invention, the wet substrate
surface may be treated with a conversion composition (described
below) and/or a sealing composition (described above), or the
substrate may be dried prior to treating the substrate surface,
such as air dried, for example, by using an air knife, by flashing
off the water by brief exposure of the substrate to a high
temperature, such as 15.degree. C. to 100.degree. C., such as
20.degree. C. to 90.degree. C., or in a heater assembly using, for
example, infrared heat, such as for 10 minutes at 70.degree. C., or
by passing the substrate between squeegee rolls.
[0054] As mentioned above, at least a portion of the substrate
surface optionally may be contacted with a conversion composition
prior to or after being contacted with the sealing composition
described above. The conversion composition may be spontaneously
depositable or electrodepositable. As used herein, "spontaneously
depositable," when used with respect to the conversion composition,
refers to a composition that is capable of reacting with and
chemically altering the substrate surface and binding to it to form
a protective layer in the absence of an externally applied voltage.
As used herein, an "electrodepositable," when used with respect to
the conversion composition, refers to a composition containing a
non-elemental metal, i.e. a metal-containing compound, complex, ion
or the like wherein the metal is not in elemental form, that is
capable of reacting with and chemically altering the substrate
surface and binding to it to form a protective layer upon the
introduction of an externally applied voltage. Such an
electrodepositable conversion composition may be applied using any
methods or parameters known to those skilled in the art.
[0055] According to the present invention, the conversion
composition may comprise a lanthanide series element cation, a
Group IIIB metal cation and/or a Group IVB metal cation. The
conversion composition also may further comprise an ion of a Group
IIA metal, a Group VB metal, a Group VIB metal, a Group VIIB metal,
and/or a Group XII metal (together with the lanthanide series
cation, the Group IIIB metal cation, and/or the Group IVB metal
cation, referred to collectively herein as "conversion composition
metal cations").
[0056] According to the present invention, the salts of the
conversion composition metal cations may be present in the
conversion composition in an amount of at least 5 ppm, such as at
least 50 ppm, such as at least 100 ppm, (calculated as metal salt)
based on total weight of the conversion composition, and in some
instances, may be present in an amount of no more than 25000 ppm,
such as no more than 9000 ppm, such as no more than 1500
(calculated as metal salt) based on total weight of the conversion
composition. According to the present invention, the salt of the
conversion composition metal cations may be present in the
conversion composition in an amount of 5 ppm to 25000 ppm
(calculated as metal salt) based on total weight of the conversion
composition, such as 50 ppm to 9000 ppm, such as 100 ppm to 1500
ppm.
[0057] According to the present invention, the conversion
composition metal cation may be present in the conversion
composition in an amount of at least 5 ppm, such as at least 150
ppm, such as at least 300 ppm, (calculated as metal cation) based
on total weight of the conversion composition, and in some
instances may be present in the conversion composition in an amount
of no more than 25,000 ppm, such as no more than 12,500 ppm, such
as no more than 10,000 ppm, (calculated as metal cation) based on
total weight of the conversion composition. According to the
present invention, the conversion composition metal cation may be
present in the conversion composition in an amount of 5 ppm to
25,000 ppm, such as 150 ppm to 12,500 ppm, such as 300 ppm to
10,000 ppm, (calculated as metal cation) based on total weight of
the conversion composition.
[0058] According to the present invention, the lanthanide series
element cation may, for example, comprise cerium, praseodymium,
terbium, or combinations thereof; the Group IIA metal cation may
comprise magnesium; the Group IIIB metal cation may comprise
yttrium, scandium, or combinations thereof; the Group IVB metal
cation may comprise zirconium, titanium, hafnium, or combinations
thereof; the Group VB metal cation may comprise vanadium; the Group
VIB metal may comprise molybdenum; the Group VIIB metal cation may
comprise trivalent or hexavalent chromium or manganese; and the
Group XII metal cation may comprise zinc.
[0059] For example, the Group IIIB metal and/or Group IVB metal
cation used in the conversion composition may be a compound of
zirconium, titanium, hafnium, yttrium, scandium, or a mixture
thereof. Suitable compounds of zirconium include, but are not
limited to, hexafluorozirconic acid, alkali metal and ammonium
salts thereof, ammonium zirconium carbonate, zirconyl nitrate,
zirconyl sulfate, zirconium carboxylates and zirconium hydroxy
carboxylates, such as zirconium acetate, zirconium oxalate,
ammonium zirconium glycolate, ammonium zirconium lactate, ammonium
zirconium citrate, and mixtures thereof. Suitable compounds of
titanium include, but are not limited to, fluorotitanic acid and
its salts. A suitable compound of hafnium includes, but is not
limited to, hafnium nitrate. Suitable compounds of yttrium include,
but are not limited to, yttrium halides.
[0060] According to the present invention, the Group IIIB metal
cation and/or the Group IVB metal cation may be present in the
conversion composition in a total amount of at least 20 ppm metal
(calculated as metal cation), based on total weight of the
conversion composition, such as at least 50 ppm metal, or, in some
cases, at least 70 ppm metal. According to the present invention,
the Group IIIB metal cation and/or the Group IVB metal cation may
be present in the conversion composition in a total amount of no
more than 1000 ppm metal (calculated as metal cation), based on
total weight of the conversion composition, such as no more than
600 ppm metal, or, in some cases, no more than 300 ppm metal.
According to the present invention, the Group IIIB metal cation
and/or the Group IVB metal cation may be present in the conversion
composition in a total amount of 20 ppm metal to 1000 ppm metal
(calculated as metal cation), based on total weight of the
conversion composition, such as from 50 ppm metal to 600 ppm metal,
such as from 70 ppm metal to 300 ppm metal. As used herein, the
term "total amount," when used with respect to the amount of Group
IIIB metal cation and/or Group IVB metal cation, means the sum of
all Group IIIB and/or Group IV metal cations present in the
conversion composition.
[0061] According to the present invention, the salts of the
conversion composition metal cations may be present in the
conversion composition in an amount of at least 5 ppm, such as at
least 50 ppm, such as at least 100 ppm, (calculated as metal salt)
based on total weight of the conversion composition, and in some
instances, may be present in an amount of no more than 25000 ppm,
such as no more than 9000 ppm, such as no more than 1500
(calculated as total metal salt) based on total weight of the
conversion composition. According to the present invention, the
salt of the conversion composition metal cations may be present in
the conversion composition in an amount of 5 ppm to 25000 ppm, such
as 50 ppm to 9000 ppm, such as 100 ppm to 1500 ppm.
[0062] According to the present invention, the conversion
composition metal cation may be present in the conversion
composition in an amount of at least 5 ppm, such as at least 150
ppm, such as at least 300 ppm, (calculated as metal cation) based
on total weight of the conversion composition, and in some
instances may be present in the conversion composition in an amount
of no more than 25,000 ppm, such as no more than 12,500 ppm, such
as no more than 10,000 ppm, (calculated as metal cation) based on
total weight of the conversion composition. According to the
present invention, the conversion composition metal cation may be
present in the conversion composition in an amount of 5 ppm to
25,000 ppm, such as 150 ppm to 12,500 ppm, such as 300 ppm to
10,000 ppm (calculated as metal cation) based on total weight of
the conversion composition.
[0063] According to the present invention, the conversion
composition also may comprise an electropositive metal ion. As used
herein, the term "electropositive metal ion" refers to metal ions
that will be reduced by the metal substrate being treated when the
conversion solution contacts the surface of the metallic substrate.
As will be appreciated by one skilled in the art, the tendency of
chemical species to be reduced is called the reduction potential,
is expressed in volts, and is measured relative to the standard
hydrogen electrode, which is arbitrarily assigned a reduction
potential of zero. The reduction potential for several elements is
set forth in Table 2 below (according to the CRC 82.sup.nd Edition,
2001-2002). An element or ion is more easily reduced than another
element or ion if it has a voltage value, E*, in the following
table, that is more positive than the elements or ions to which it
is being compared.
TABLE-US-00002 TABLE 2 Element Reduction half-cell reaction
Voltage, E* Potassium K.sup.+ + e .fwdarw. K -2.93 Calcium
Ca.sup.2+ + 2e .fwdarw. Ca -2.87 Sodium Na.sup.+ + e .fwdarw. Na
-2.71 Magnesium Mg.sup.2+ + 2e .fwdarw. Mg -2.37 Aluminum Al.sup.3+
+ 3e .fwdarw. Al -1.66 Zinc Zn.sup.2+ + 2e .fwdarw. Zn -0.76 Iron
Fe.sup.2+ + 2e .fwdarw. Fe -0.45 Nickel Ni.sup.2+ + 2e .fwdarw. Ni
-0.26 Tin Sn.sup.2+ + 2e .fwdarw. Sn -0.14 Lead Pb.sup.2+ + 2e
.fwdarw. Pb -0.13 Hydrogen 2H.sup.+ + 2e .fwdarw. H.sub.2 -0.00
Copper Cu.sup.2+ + 2e .fwdarw. Cu 0.34 Mercury Hg.sub.2.sup.2+ + 2e
.fwdarw. 2Hg 0.80 Silver Ag.sup.+ + e .fwdarw. Ag 0.80 Gold
Au.sup.3+ + 3e .fwdarw. Au 1.50
[0064] Thus, as will be apparent, when the metal substrate
comprises one of the materials listed earlier, such as cold rolled
steel, hot rolled steel, steel coated with zinc metal, zinc
compounds, or zinc alloys, hot-dipped galvanized steel, galvanealed
steel, steel plated with zinc alloy, aluminum alloys, aluminum
plated steel, aluminum alloy plated steel, magnesium and magnesium
alloys, suitable electropositive metals for deposition thereon
include, for example, nickel, copper, silver, and gold, as well
mixtures thereof.
[0065] According to the present invention, when the electropositive
metal comprises copper, both soluble and insoluble compounds may
serve as a source of copper ions in the conversion compositions.
For example, the supplying source of copper ions in the conversion
composition may be a water soluble copper compound. Specific
examples of such compounds include, but are not limited to, copper
cyanide, copper potassium cyanide, copper sulfate, copper nitrate,
copper pyrophosphate, copper thiocyanate, disodium copper
ethylenediaminetetraacetate tetrahydrate, copper bromide, copper
oxide, copper hydroxide, copper chloride, copper fluoride, copper
gluconate, copper citrate, copper lauroyl sarcosinate, copper
formate, copper acetate, copper propionate, copper butyrate, copper
lactate, copper oxalate, copper phytate, copper tartrate, copper
malate, copper succinate, copper malonate, copper maleate, copper
benzoate, copper salicylate, copper aspartate, copper glutamate,
copper fumarate, copper glycerophosphate, sodium copper
chlorophyllin, copper fluorosilicate, copper fluoroborate and
copper iodate, as well as copper salts of carboxylic acids in the
homologous series formic acid to decanoic acid, copper salts of
polybasic acids in the series oxalic acid to suberic acid, and
copper salts of hydroxycarboxylic acids, including glycolic,
lactic, tartaric, malic and citric acids.
[0066] When copper ions supplied from such a water-soluble copper
compound are precipitated as an impurity in the form of copper
sulfate, copper oxide, etc., it may be desirable to add a
complexing agent that suppresses the precipitation of copper ions,
thus stabilizing them as a copper complex in the composition.
[0067] According to the present invention, the copper compound may
be added as a copper complex salt such as K.sub.3Cu(CN).sub.4 or
Cu-EDTA, which can be present stably in the conversion composition
on its own, but it is also possible to form a copper complex that
can be present stably in the conversion composition by combining a
complexing agent with a compound that is difficult to solubilize on
its own. Examples thereof include a copper cyanide complex formed
by a combination of CuCN and KCN or a combination of CuSCN and KSCN
or KCN, and a Cu-EDTA complex formed by a combination of CuSO.sub.4
and EDTA.2Na.
[0068] With regard to the complexing agent, a compound that can
form a complex with copper ions can be used; examples thereof
include inorganic compounds such as cyanide compounds and
thiocyanate compounds, and polycarboxylic acids, and specific
examples thereof include ethylenediaminetetraacetic acid, salts of
ethylenediaminetetraacetic acid such as dihydrogen disodium
ethylenediaminetetraacetate dihydrate, aminocarboxylic acids such
as nitrilotriacetic acid and iminodiacetic acid, oxycarboxylic
acids such as citric acid and tartaric acid, succinic acid, oxalic
acid, ethylenediaminetetramethylenephosphonic acid, and glycine,
and organophosphonates such as 1-hydroxethylidene-1,1-diphosphonic
acid (commercially available from Italmatch Chemicals as Dequest
2010).
[0069] According to the present invention, the electropositive
metal ion may be present in the conversion composition in an amount
of at least 2 ppm (calculated as metal ion) based on the total
weight of the conversion composition, such as at least 4 ppm, such
as at least 6 ppm, such as at least 8 ppm, such as at least 10 ppm.
According to the present invention, the electropositive metal ion
may be present in the conversion composition in an amount of no
more than 100 ppm (calculated as metal ion) based on the total
weight of the conversion composition, such as no more than 80 ppm,
such as no more than 60 ppm, such as no more than 40 ppm, such as
no more than 20 ppm. According to the present invention, the
electropositive metal ion may be present in the conversion
composition in an amount of from 2 ppm to 100 ppm (calculated as
metal ion) based on the total weight of the conversion composition,
such as from 4 ppm to 80 ppm, such as from 6 ppm to 60 ppm, such as
from 8 ppm to 40 ppm, such as from 10 ppm to 20 ppm. The amount of
electropositive metal ion in the conversion composition can range
between the recited values inclusive of the recited values.
[0070] According to the present invention, a source of fluoride may
be present in the conversion composition. As used herein the amount
of fluoride disclosed or reported in the conversion composition is
referred to as "free fluoride," as measured in part per millions of
fluoride. Free fluoride is defined above as being able to be
measured by a fluoride-selective ISE. In addition to free fluoride,
a conversion may also contain "bound fluoride, which is described
above. The sum of the concentrations of the bound and free fluoride
equal the total fluoride, which can be determined as described
above. The total fluoride in the conversion composition can be
supplied by hydrofluoric acid, as well as alkali metal and ammonium
fluorides or hydrogen fluorides. Additionally, total fluoride in
the conversion composition may be derived from Group IVB metals
present in the conversion composition, including, for example,
hexafluorozirconic acid or hexafluorotitanic acid. Other complex
fluorides, such as H.sub.2SiF.sub.6 or HBF.sub.4, can be added to
the conversion composition to supply total fluoride. The skilled
artisan will understand that the presence of free fluoride in the
conversion bath can impact conversion deposition and etching of the
substrate, hence it is critical to measure this bath parameter. The
levels of free fluoride will depend on the pH and the addition of
chelators into the conversion bath and indicates the degree of
fluoride association with the metal ions/protons present in the
conversion bath. For example, conversion compositions of identical
total fluoride levels can have different free fluoride levels which
will be influenced by the pH and chelators present in the
conversion solution.
[0071] According to the present invention, the total fluoride of
the conversion composition may be present in an amount of at least
25 ppm, based on a total weight of the conversion composition, such
as at least 100 ppm fluoride, such as at least 200 ppm fluoride.
According to the present invention, the total fluoride of the
conversion composition may be present in an amount of no more than
5000 ppm, based on a total weight of the conversion composition,
such as no more than 2000 ppm fluoride, such as no more than 1000
ppm fluoride. According to the present invention, the total
fluoride of the conversion composition may be present in an amount
of 10 ppm fluoride to 5000 ppm fluoride, based on a total weight of
the conversion composition, such as 100 ppm fluoride to 2000 ppm,
such as no more than 200 ppm fluoride to 1000 ppm fluoride.
[0072] According to the present invention, the free fluoride of the
conversion composition may be present in an amount of at least 15
ppm, based on a total weight of the conversion composition, such as
at least 50 ppm free fluoride, such as at least 100 ppm free
fluoride, such as at least 200 ppm free fluoride. According to the
present invention, the free fluoride of the conversion composition
may be present in an amount of no more than 2500 ppm, based on a
total weight of the conversion composition, such as no more than
1000 ppm free fluoride, such as no more than 500 ppm free fluoride,
such as no more than 250 ppm free fluoride. According to the
present invention, the free fluoride of the conversion composition
may be present in an amount of 15 ppm free fluoride to 2500 ppm
free fluoride, based on a total weight of the conversion
composition, such as 50 ppm fluoride to 1000 ppm, such as no more
than 200 ppm free fluoride to 500 ppm free fluoride, such as no
more than 100 ppm free fluoride to 250 ppm free fluoride.
[0073] According to the present invention, the conversion
composition also may comprise a lithium cation. According to the
invention, the conversion composition may further comprise an anion
that may be suitable for forming a salt with the lithium cation.
Non-limiting examples of suitable lithium salts include lithium
nitrate, lithium sulfate, lithium fluoride, lithium chloride,
lithium hydroxide, lithium carbonate, lithium iodide, and
combinations thereof.
[0074] According to the present invention, the lithium cation may
be present in the conversion composition in an amount of at least 2
ppm (as lithium cation) based on a total weight of the conversion
composition, such as at least 5 ppm, such as at least 25 ppm, such
as at least 75 ppm, and in some instances, may be present in amount
of no more than 500 ppm, based on a total weight of the conversion
composition, such as no more than 250 ppm, such as no more than 125
ppm, such as no more than 100 ppm. According to the present
invention, the lithium cation may be present in the conversion
composition in an amount of 2 ppm to 500 ppm (as lithium cation)
based on a total weight of the conversion composition, such as 5
ppm to 250 ppm, such as 25 ppm to 125 ppm, such as 75 ppm to 100
ppm. The amount of lithium cation in the conversion composition can
range between the recited values inclusive of the recited
values.
[0075] According to the present invention, the conversion
composition may also comprise a molybdenum cation. According to the
invention, the conversion composition may further comprise an anion
that may be suitable for forming a salt with the molybdenum cation.
Non-limiting examples of suitable molybdenum salts include sodium
molybdate, calcium molybdate, potassium molybdate, ammonium
molybdate, molybdenum chloride, molybdenum acetate, molybdenum
sulfamate, molybdenum formate, molybdenum lactate, and combinations
thereof.
[0076] According to the present invention, molybdenum cation may be
present in the conversion composition in an amount of at least 5
ppm (as molybdenum cation) based on a total weight of the
conversion composition, such as at least 25 ppm, such as 100 ppm,
and in some instances, may be present in the conversion composition
in an amount of no more than 500 ppm, based on total weight of the
conversion composition, such as no more than 250 ppm, such as no
more than 150 ppm. According to the present invention, molybdenum
may be present in the conversion composition in an amount of 5 ppm
to 500 ppm (as molybdenum cation) based on total weight of the
conversion composition, such as 25 ppm to 250 ppm, such as 100 ppm
to 150 ppm. The amount of molybdenum in the conversion composition
can range between the recited values inclusive of the recited
values.
[0077] According to the present invention, the conversion
composition may further comprise an anion that may be suitable for
forming a salt with the conversion composition metal cations, such
as a halogen, a nitrate, a sulfate, a phosphate, a silicate
(orthosilicates and metasilicates), carbonates, hydroxides, and the
like. According to the present invention, the conversion
composition metal salt may be present in the conversion composition
in an amount of at least 50 ppm (calculated as metal salt) based on
total weight of the conversion composition, such as at least 1000
ppm, and in some instances, may be present in an amount of no more
than 30,000 ppm, such as no more than 2000 ppm. According to the
present invention, the conversion composition metal salt may be
present in an amount of 50 ppm to 30,000 ppm, such as 1000 ppm to
2000 ppm (calculated as metal salt) based on total weight of the
conversion composition.
[0078] According to the present invention, the halogen may be
present in the conversion composition, if at all, in an amount of
at least 5 ppm (calculated as anion) based on total weight of the
conversion composition, such as at least 50 ppm, such as at least
150 ppm, such as at least 500 ppm, and may be present in an amount
of no more than 25,000 ppm (calculated as anion) based on total
weight of the conversion composition, such as no more than 18,500
ppm, such as no more than 4000 ppm, such as no more than 2000 ppm.
According to the present invention, the halogen may be present in
the conversion composition, if at all, in an amount of 5 ppm to
25,000 ppm (calculated as anion) based on total weight of the
conversion composition, such as 50 ppm to 18,500 ppm, such as 150
ppm to 4000, such as 500 ppm to 2000 ppm.
[0079] According to the present invention, the nitrate may be
present in the conversion composition, if at all, in an amount of
at least 2 ppm (calculated as anion) based on total weight of the
conversion composition, such as at least 50 ppm, such as at least
250 ppm, and may be present in an amount of no more than 10,000 ppm
(calculated as anion) based on total weight of the conversion
composition, such as no more than 5000 ppm, such as no more than
2500 ppm. According to the present invention, the halogen may be
present in the conversion composition, if at all, in an amount of 2
ppm to 10,000 ppm (calculated as anion) based on total weight of
the conversion composition, such as 50 ppm to 5000 ppm, such as 250
ppm to 2500 ppm.
[0080] According to the present invention, the conversion
composition may, in some instances, comprise an oxidizing agent.
Non-limiting examples of the oxidizing agent include peroxides,
persulfates, perchlorates, hypochlorite, nitric acid, sparged
oxygen, bromates, peroxi-benzoates, ozone, or combinations
thereof.
[0081] According to the present invention, the oxidizing agent may
be present, if at all, in an amount of at least 100 ppm, such as at
least 500 ppm, based on total weight of the conversion composition,
and in some instances, may be present in an amount of no more than
13,000 ppm, such as no more than 3000 ppm, based on total weight of
the conversion composition. In some instances, the oxidizing agent
may be present in the conversion composition, if at all, in an
amount of 100 ppm to 13,000 ppm, such as 500 ppm to 3000 ppm, based
on total weight of the conversion composition.
[0082] According to the present invention, the conversion
composition may exclude chromium or chromium-containing compounds.
As used herein, the term "chromium-containing compound" refers to
materials that include hexavalent chromium. Non-limiting examples
of such materials include chromic acid, chromium trioxide, chromic
acid anhydride, dichromate salts, such as ammonium dichromate,
sodium dichromate, potassium dichromate, and calcium, barium,
magnesium, zinc, cadmium, and strontium dichromate. When a
conversion composition and/or a coating or a layer, respectively,
formed from the same is substantially free, essentially free, or
completely free of chromium, this includes chromium in any form,
such as, but not limited to, the hexavalent chromium-containing
compounds listed above.
[0083] Thus, optionally, according to the present invention, the
present conversion compositions and/or coatings or layers,
respectively, deposited from the same may be substantially free,
may be essentially free, and/or may be completely free of one or
more of any of the elements or compounds listed in the preceding
paragraph. A conversion composition and/or coating or layer,
respectively, formed from the same that is substantially free of
chromium or derivatives thereof means that chromium or derivatives
thereof are not intentionally added, but may be present in trace
amounts, such as because of impurities or unavoidable contamination
from the environment. In other words, the amount of material is so
small that it does not affect the properties of the conversion
composition; in the case of chromium, this may further include that
the element or compounds thereof are not present in the conversion
compositions and/or coatings or layers, respectively, formed from
the same in such a level that it causes a burden on the
environment. The term "substantially free" means that the
conversion compositions and/or coating or layers, respectively,
formed from the same contain less than 10 ppm of any or all of the
elements or compounds listed in the preceding paragraph, based on
total weight of the composition or the layer, respectively, if any
at all. The term "essentially free" means that the conversion
compositions and/or coatings or layers, respectively, formed from
the same contain less than 1 ppm of any or all of the elements or
compounds listed in the preceding paragraph, if any at all. The
term "completely free" means that the conversion compositions
and/or coatings or layers, respectively, formed from the same
contain less than 1 ppb of any or all of the elements or compounds
listed in the preceding paragraph, if any at all.
[0084] According to the present invention, the conversion
composition may, in some instances, exclude phosphate ions or
phosphate-containing compounds and/or the formation of sludge, such
as aluminum phosphate, iron phosphate, and/or zinc phosphate,
formed in the case of using a treating agent based on zinc
phosphate. As used herein, "phosphate-containing compounds" include
compounds containing the element phosphorous such as ortho
phosphate, pyrophosphate, metaphosphate, tripolyphosphate,
organophosphonates, and the like, and can include, but are not
limited to, monovalent, divalent, or trivalent cations such as:
sodium, potassium, calcium, zinc, nickel, manganese, aluminum
and/or iron. When a composition and/or a layer or coating
comprising the same is substantially free, essentially free, or
completely free of phosphate, this includes phosphate ions or
compounds containing phosphate in any form.
[0085] Thus, according to the present invention, conversion
composition and/or layers deposited from the same may be
substantially free, or in some cases may be essentially free, or in
some cases may be completely free, of one or more of any of the
ions or compounds listed in the preceding paragraph. A conversion
composition and/or layers deposited from the same that is
substantially free of phosphate means that phosphate ions or
compounds containing phosphate are not intentionally added, but may
be present in trace amounts, such as because of impurities or
unavoidable contamination from the environment. In other words, the
amount of material is so small that it does not affect the
properties of the composition; this may further include that
phosphate is not present in the conversion compositions and/or
layers deposited from the same in such a level that they cause a
burden on the environment. The term "substantially free" means that
the conversion compositions and/or layers deposited from the same
contain less than 5 ppm of any or all of the phosphate anions or
compounds listed in the preceding paragraph, based on total weight
of the composition or the layer, respectively, if any at all. The
term "essentially free" means that the conversion compositions
and/or layers comprising the same contain less than 1 ppm of any or
all of the phosphate anions or compounds listed in the preceding
paragraph. The term "completely free" means that the conversion
compositions and/or layers comprising the same contain less than 1
ppb of any or all of the phosphate anions or compounds listed in
the preceding paragraph, if any at all.
[0086] According to the present invention, the pH of the conversion
composition may be 1.0 to 4.5, such as 3 to 4, and may be adjusted
using, for example, any acid and/or base as is necessary. According
to the present invention, the pH of the conversion composition may
be maintained through the inclusion of an acidic material,
including water soluble and/or water dispersible acids, such as
nitric acid, sulfuric acid, and/or phosphoric acid. According to
the present invention, the pH of the composition may be maintained
through the inclusion of a basic material, including water soluble
and/or water dispersible bases, such as sodium hydroxide, sodium
carbonate, potassium hydroxide, ammonium hydroxide, ammonia, and/or
amines such as triethylamine, methylethyl amine, or mixtures
thereof.
[0087] The conversion composition may comprise an aqueous medium
and may optionally contain other materials such as nonionic
surfactants and auxiliaries conventionally used in the art of
conversion compositions. In the aqueous medium, water dispersible
organic solvents, for example, alcohols with up to about 8 carbon
atoms such as methanol, isopropanol, and the like, may be present;
or glycol ethers such as the monoalkyl ethers of ethylene glycol,
diethylene glycol, or propylene glycol, and the like. When present,
water dispersible organic solvents are typically used in amounts up
to about ten percent by volume, based on the total volume of
aqueous medium.
[0088] Other optional materials include surfactants that function
as defoamers or substrate wetting agents. Anionic, cationic,
amphoteric, and/or nonionic surfactants may be used. Defoaming
surfactants may optionally be present at levels up to 1 weight
percent, such as up to 0.1 percent by weight, and wetting agents
are typically present at levels up to 2 percent, such as up to 0.5
percent by weight, based on the total weight of the conversion
composition.
[0089] Optionally, according to the present invention, the
conversion composition and/or films deposited or formed therefrom
may further comprise silicon in amounts of at least 10 ppm, based
on total weight of the conversion composition, such as at least 20
ppm, such as at least 50 ppm. According to the present invention,
the conversion composition and/or films deposited or formed
therefrom may comprise silicon in amounts of less than 500 ppm,
based on total weight of the conversion composition, such as less
than 250 ppm, such as less than 100 ppm. According to the present
invention, the conversion composition and/or films deposited or
formed therefrom may comprise silicon in amounts of 10 ppm to 500
ppm, based on total weight of the conversion composition, such as
20 ppm to 250 ppm, such as 50 ppm to 100 ppm. Alternatively, the
conversion composition of the present invention and/or films
deposited or formed therefrom may be substantially free, or, in
some cases, completely free of silicon.
[0090] The conversion composition may comprise a carrier, often an
aqueous medium, so that the composition is in the form of a
solution or dispersion of the lanthanide and/or Group IIIB metal in
the carrier. In these embodiments, the solution or dispersion may
be brought into contact with the substrate by any of a variety of
known techniques, such as dipping or immersion, spraying,
intermittent spraying, dipping followed by spraying, spraying
followed by dipping, brushing, or roll-coating. According to the
invention, the solution or dispersion when applied to the metal
substrate is at a temperature ranging from 40.degree. F. to
160.degree. F., such as 60.degree. F. to 110.degree. F., such as
70.degree. F. to 90.degree. F. For example, the conversion process
may be carried out at ambient or room temperature. The contact time
is often from 30 seconds to 15 minutes, such as 4 minutes to 10
minutes.
[0091] According to the present invention, following the contacting
with the conversion composition, the substrate optionally may be
air dried at room temperature or may be dried with hot air, for
example, by using an air knife, by flashing off the water by brief
exposure of the substrate to a high temperature, such as by drying
the substrate in an oven at 15.degree. C. to 100.degree. C., such
as 20.degree. C. to 90.degree. C., or in a heater assembly using,
for example, infrared heat, such as for 10 minutes at 70.degree.
C., or by passing the substrate between squeegee rolls. According
to the present invention, following the contacting with the
conversion composition, the substrate optionally may be rinsed with
tap water, deionized water, and/or an aqueous solution of rinsing
agents in order to remove any residue and then optionally may be
dried, for example air dried or dried with hot air as described in
the preceding sentence.
[0092] According to the present invention, the level of the
lanthanide, Group IIIB metal, and/or Group IVB metal in the film
formed on the substrate surface from the conversion composition is
at least 100 counts greater than on a surface of a substrate that
does not have the film thereon as measured by X-ray fluorescence
(measured using X-Met 7500, Oxford Instruments; operating
parameters 60 second timed assay, 15 Kv, 45 .mu.A, filter 3,
T(p)=1.5 .mu.s for lanthanides, Group IIIB metals, and Group IVB
metals except zirconium; operating parameters 60 second timed
assay, 40 Kv, 10 .mu.A, filter 4, T(p)=1.5 .mu.s for
zirconium).
[0093] According to the present invention, the substrate having
been contacted with the conversion composition and having the layer
formed from the sealing composition has at least a 50% reduction in
the number of pits on the substrate surface compared to a substrate
having the film formed from the conversion composition or the layer
formed from the sealing composition but not the film and the seal
following 3 day exposure in neutral salt spray cabinet operated
according to ASTM B117.
[0094] According to the present invention, the substrate having the
film formed from the conversion composition and the layer formed
from the sealing composition has at least a 50% reduction in the
number of pits on the substrate surface compared to a substrate
having the film formed from the conversion composition or the layer
formed from the sealing composition but not the film and the seal
following 3 day exposure in neutral salt spray cabinet operated
according to ASTM BI 17.
[0095] According to the present invention, disclosed herein is a
substrate comprising, or in some instances consisting essentially
of, or in some instances consisting of, a layer having a thickness
of 25 nm to 250 nm formed from a sealing composition comprising, or
in some instances consisting essentially of, or in some instances,
consisting of, a lithium source. According to the present
invention, the substrate may comprise an aluminum alloy comprising
copper in an amount of 1 percent by weight to 10 percent by
weight.
[0096] According to the present invention, disclosed herein is a
substrate comprising, or in some instances consisting essentially
of, or in some instances consisting of: a film formed from a
conversion composition comprising, or in some cases consisting
essentially of, or in some instances consisting of, a lanthanide, a
Group IIIB metal, a Group IVB metal, or combinations thereof,
wherein the level of the lanthanide, Group IIIB metal, and/or Group
IVB metal in the film is at least 100 counts greater than on a
surface of a substrate that does not have the film thereon as
measured by X-ray fluorescence (measured using X-Met 7500, Oxford
Instruments; operating parameters 60 second timed assay, 15 Kv, 45
.mu.A, filter 3, T(p)=1.5 .mu.s for lanthanides, Group IIIB metals,
and Group IVB metals except zirconium; operating parameters 60
second timed assay, 40 Kv, 10 .mu.A, filter 4, T(p)=1.5 .mu.s for
zirconium); and a layer formed from a sealing composition
comprising, or in some instances consisting essentially of, or in
some instances consisting of, a lithium source.
[0097] According to the present invention, disclosed herein is a
method of treating a substrate comprising, or in some instances
consisting essentially of, or in some instances consisting of,
contacting at least a portion of the substrate surface with a
sealing composition comprising, or in some instances consisting
essentially of, or in some instances, consisting of, a lithium
source. According to the present invention, the substrate may
comprise an aluminum alloy comprising copper in an amount of 1
percent by weight to 10 percent by weight.
[0098] According to the present invention, disclosed herein is a
method of treating a substrate, comprising, or in some instances
consisting essentially of, or in some instances consisting of, (a)
contacting at least a portion of the substrate surface with a
conversion composition comprising, or in some instances consisting
essentially of, or in some instances consisting of, a lanthanide, a
Group IIIB metal, a Group IVB metal, or combinations thereof; and
(b) contacting at least a portion of the substrate surface
contacted with the conversion composition with a sealing
composition comprising, or in some instances consisting essentially
of, or in some instances consisting of, a lithium source.
[0099] It has been surprisingly discovered that the combination
contacting a substrate surface with a lanthanide-containing
conversion composition and a lithium-containing sealing composition
that includes either Group VB salt or a Group VIB salt further
reduced the level of pitting on the substrate surface following 3
day exposure in neutral salt spray cabinet operated according to
ASTM B117 compared to a substrate surface that has been contacted
with the conversion composition and a sealing composition that does
not include the Group VB salt or Group VIB salt. These results were
unexpected.
[0100] It also has been surprisingly discovered that the
combination of a film formed from a lanthanide-containing
conversion composition with a layer formed from a
lithium-containing sealing composition results in at least a 50%
reduction in the number of pits on the substrate surface compared
to a substrate surface that has the conversion composition film or
the sealing composition layer but not both following 7 day exposure
in neutral salt spray cabinet operated according to ASTM BI 17.
These results were unexpected.
[0101] Notably, on sanded substrates, corrosion performance was
markedly improved on when such sanded substrates were treated
according to the system and method of the present invention.
[0102] According to the present invention, after the substrate is
contacted with the sealing composition, a coating composition
comprising a film-forming resin may be deposited onto at least a
portion of the surface of the substrate that has been contacted
with the sealing composition. Any suitable technique may be used to
deposit such a coating composition onto the substrate, including,
for example, brushing, dipping, flow coating, spraying and the
like. In some instances, however, as described in more detail
below, such depositing of a coating composition may comprise an
electrocoating step wherein an electrodepositable composition is
deposited onto a metal substrate by electrodeposition. In certain
other instances, as described in more detail below, such depositing
of a coating composition comprises a powder coating step. In still
other instances, the coating composition may be a liquid coating
composition.
[0103] According to the present invention, the coating composition
may comprise a thermosetting film-forming resin or a thermoplastic
film-forming resin. As used herein, the term "film-forming resin"
refers to resins that can form a self-supporting continuous film on
at least a horizontal surface of a substrate upon removal of any
diluents or carriers present in the composition or upon curing at
ambient or elevated temperature. Conventional film-forming resins
that may be used include, without limitation, those typically used
in automotive OEM coating compositions, automotive refinish coating
compositions, industrial coating compositions, architectural
coating compositions, coil coating compositions, and aerospace
coating compositions, among others. As used herein, the term
"thermosetting" refers to resins that "set" irreversibly upon
curing or crosslinking, wherein the polymer chains of the polymeric
components are joined together by covalent bonds. This property is
usually associated with a cross-linking reaction of the composition
constituents often induced, for example, by heat or radiation.
Curing or crosslinking reactions also may be carried out under
ambient conditions. Once cured or crosslinked, a thermosetting
resin will not melt upon the application of heat and is insoluble
in solvents. As used herein, the term "thermoplastic" refers to
resins that comprise polymeric components that are not joined by
covalent bonds and thereby can undergo liquid flow upon heating and
are soluble in solvents.
[0104] As previously indicated, according to the present invention,
an electrodepositable coating composition comprising a
water-dispersible, ionic salt group-containing film-forming resin
that may be deposited onto the substrate by an electrocoating step
wherein the electrodepositable coating composition is deposited
onto the metal substrate by electrodeposition.
[0105] The ionic salt group-containing film-forming polymer may
comprise a cationic salt group containing film-forming polymer for
use in a cationic electrodepositable coating composition. As used
herein, the term "cationic salt group-containing film-forming
polymer" refers to polymers that include at least partially
neutralized cationic groups, such as sulfonium groups and ammonium
groups, that impart a positive charge. The cationic salt
group-containing film-forming polymer may comprise active hydrogen
functional groups, including, for example, hydroxyl groups, primary
or secondary amine groups, and thiol groups. Cationic salt
group-containing film-forming polymers that comprise active
hydrogen functional groups may be referred to as active
hydrogen-containing, cationic salt group-containing film-forming
polymers. Examples of polymers that are suitable for use as the
cationic salt group-containing film-forming polymer include, but
are not limited to, alkyd polymers, acrylics, polyepoxides,
polyamides, polyurethanes, polyureas, polyethers, and polyesters,
among others.
[0106] The cationic salt group-containing film-forming polymer may
be present in the cationic electrodepositable coating composition
in an amount of 40% to 90% by weight, such as 50% to 80% by weight,
such as 60% to 75% by weight, based on the total weight of the
resin solids of the electrodepositable coating composition. As used
herein, the "resin solids" include the ionic salt group-containing
film-forming polymer, curing agent, and any additional
water-dispersible non-pigmented component(s) present in the
electrodepositable coating composition.
[0107] Alternatively, the ionic salt group containing film-forming
polymer may comprise an anionic salt group containing film-forming
polymer for use in an anionic electrodepositable coating
composition. As used herein, the term "anionic salt group
containing film-forming polymer" refers to an anionic polymer
comprising at least partially neutralized anionic functional
groups, such as carboxylic acid and phosphoric acid groups that
impart a negative charge. The anionic salt group-containing
film-forming polymer may comprise active hydrogen functional
groups. Anionic salt group-containing film-forming polymers that
comprise active hydrogen functional groups may be referred to as
active hydrogen-containing, anionic salt group-containing
film-forming polymers.
[0108] The anionic salt group-containing film-forming polymer may
comprise base-solubilized, carboxylic acid group-containing
film-forming polymers such as the reaction product or adduct of a
drying oil or semi-drying fatty acid ester with a dicarboxylic acid
or anhydride; and the reaction product of a fatty acid ester,
unsaturated acid or anhydride and any additional unsaturated
modifying materials which are further reacted with polyol. Also
suitable are the at least partially neutralized interpolymers of
hydroxy-alkyl esters of unsaturated carboxylic acids, unsaturated
carboxylic acid and at least one other ethylenically unsaturated
monomer. Still another suitable anionic electrodepositable resin
comprises an alkyd-aminoplast vehicle, i.e., a vehicle containing
an alkyd resin and an amine-aldehyde resin. Another suitable
anionic electrodepositable resin composition comprises mixed esters
of a resinous polyol. Other acid functional polymers may also be
used such as phosphatized polyepoxide or phosphatized acrylic
polymers. Exemplary phosphatized polyepoxides are disclosed in U.S.
Patent Application Publication No. 2009-0045071 at [0004]-[0015]
and U.S. patent application Ser. No. 13/232,093 at [0014]-[0040],
the cited portions of which being incorporated herein by
reference.
[0109] The anionic salt group-containing film-forming polymer may
be present in the anionic electrodepositable coating composition in
an amount 50% to 90%, such as 55% to 80%, such as 60% to 75%, based
on the total weight of the resin solids of the electrodepositable
coating composition.
[0110] The electrodepositable coating composition may further
comprise a curing agent. The curing agent may react with the
reactive groups, such as active hydrogen groups, of the ionic salt
group-containing film-forming polymer to effectuate cure of the
coating composition to form a coating. Non-limiting examples of
suitable curing agents are at least partially blocked
polyisocyanates, aminoplast resins and phenoplast resins, such as
phenolformaldehyde condensates including allyl ether derivatives
thereof.
[0111] The curing agent may be present in the cationic
electrodepositable coating composition in an amount of 10% to 60%
by weight, such as 20% to 50% by weight, such as 25% to 40% by
weight, based on the total weight of the resin solids of the
electrodepositable coating composition. Alternatively, the curing
agent may be present in the anionic electrodepositable coating
composition in an amount of 10% to 50% by weight, such as 20% to
45% by weight, such as 25% to 40% by weight, based on the total
weight of the resin solids of the electrodepositable coating
composition.
[0112] The electrodepositable coating composition may further
comprise other optional ingredients, such as a pigment composition
and, if desired, various additives such as fillers, plasticizers,
anti-oxidants, biocides, UV light absorbers and stabilizers,
hindered amine light stabilizers, defoamers, fungicides, dispersing
aids, flow control agents, surfactants, wetting agents, or
combinations thereof.
[0113] The electrodepositable coating composition may comprise
water and/or one or more organic solvent(s). Water can for example
be present in amounts of 40% to 90% by weight, such as 50% to 75%
by weight, based on total weight of the electrodepositable coating
composition. If used, the organic solvents may typically be present
in an amount of less than 10% by weight, such as less than 5% by
weight, based on total weight of the electrodepositable coating
composition. The electrodepositable coating composition may in
particular be provided in the form of an aqueous dispersion. The
total solids content of the electrodepositable coating composition
may be from 1% to 50% by weight, such as 5% to 40% by weight, such
as 5% to 20% by weight, based on the total weight of the
electrodepositable coating composition. As used herein, "total
solids" refers to the non-volatile content of the
electrodepositable coating composition, i.e., materials which will
not volatilize when heated to 110.degree. C. for 15 minutes.
[0114] The cationic electrodepositable coating composition may be
deposited upon an electrically conductive substrate by placing the
composition in contact with an electrically conductive cathode and
an electrically conductive anode, with the surface to be coated
being the cathode. Alternatively, the anionic electrodepositable
coating composition may be deposited upon an electrically
conductive substrate by placing the composition in contact with an
electrically conductive cathode and an electrically conductive
anode, with the surface to be coated being the anode. An adherent
film of the electrodepositable coating composition is deposited in
a substantially continuous manner on the cathode or anode,
respectively, when a sufficient voltage is impressed between the
electrodes. The applied voltage may be varied and can be, for
example, as low as one volt to as high as several thousand volts,
such as between 50 and 500 volts. Current density is usually
between 1.0 ampere and 15 amperes per square foot (10.8 to 161.5
amperes per square meter) and tends to decrease quickly during the
electrodeposition process, indicating formation of a continuous
self-insulating film.
[0115] Once the cationic or anionic electrodepositable coating
composition is electrodeposited over at least a portion of the
electroconductive substrate, the coated substrate is heated to a
temperature and for a time sufficient to cure the electrodeposited
coating on the substrate. For cationic electrodeposition, the
coated substrate may be heated to a temperature ranging from
250.degree. F. to 450.degree. F. (121.1.degree. C. to 232.2.degree.
C.), such as from 275.degree. F. to 400.degree. F. (135.degree. C.
to 204.4.degree. C.), such as from 300.degree. F. to 360.degree. F.
(149.degree. C. to 180.degree. C.). For anionic electrodeposition,
the coated substrate may be heated to a temperature ranging from
200.degree. F. to 450.degree. F. (93.degree. C. to 232.2.degree.
C.), such as from 275.degree. F. to 400.degree. F. (135.degree. C.
to 204.4.degree. C.), such as from 300.degree. F. to 360.degree. F.
(149.degree. C. to 180.degree. C.), such as 200.degree. F. to
210.2.degree. F. (93.degree. C. to 99.degree. C.). The curing time
may be dependent upon the curing temperature as well as other
variables, for example, the film thickness of the electrodeposited
coating, level and type of catalyst present in the composition and
the like. For example, the curing time can range from 10 minutes to
60 minutes, such as 20 to 40 minutes. The thickness of the
resultant cured electrodeposited coating may range from 2 to 50
microns.
[0116] Alternatively, as mentioned above, according to the present
invention, after the substrate has been contacted with the sealing
composition, a powder coating composition may then be deposited
onto at least a portion of the surface of the substrate. As used
herein, "powder coating composition" refers to a coating
composition which is completely free of water and/or solvent.
Accordingly, the powder coating composition disclosed herein is not
synonymous to waterborne and/or solvent-borne coating compositions
known in the art.
[0117] According to the present invention, the powder coating
composition may comprise (a) a film forming polymer having a
reactive functional group; and (b) a curing agent that is reactive
with the functional group. Examples of powder coating compositions
that may be used in the present invention include the
polyester-based ENVIROCRON line of powder coating compositions
(commercially available from PPG Industries, Inc.) or
epoxy-polyester hybrid powder coating compositions. Alternative
examples of powder coating compositions that may be used in the
present invention include low temperature cure thermosetting powder
coating compositions comprising (a) at least one tertiary aminourea
compound, at least one tertiary aminourethane compound, or mixtures
thereof, and (b) at least one film-forming epoxy-containing resin
and/or at least one siloxane-containing resin (such as those
described in U.S. Pat. No. 7,470,752, assigned to PPG Industries,
Inc. and incorporated herein by reference); curable powder coating
compositions generally comprising (a) at least one tertiary
aminourea compound, at least one tertiary aminourethane compound,
or mixtures thereof, and (b) at least one film-forming
epoxy-containing resin and/or at least one siloxane-containing
resin (such as those described in U.S. Pat. No. 7,432,333, assigned
to PPG Industries, Inc. and incorporated herein by reference); and
those comprising a solid particulate mixture of a reactive
group-containing polymer having a T.sub.g of at least 30.degree. C.
(such as those described in U.S. Pat. No. 6,797,387, assigned to
PPG Industries, Inc. and incorporated herein by reference).
[0118] After deposition of the powder coating composition, the
coating is often heated to cure the deposited composition. The
heating or curing operation is often carried out at a temperature
in the range of from 150.degree. C. to 200.degree. C., such as from
170.degree. C. to 190.degree. C., for a period of time ranging from
10 to 20 minutes. According to the invention, the thickness of the
resultant film is from 50 microns to 125 microns.
[0119] As mentioned above, according to the present invention, the
coating composition may be a liquid coating composition. As used
herein, "liquid coating composition" refers to a coating
composition which contains a portion of water and/or solvent.
Accordingly, the liquid coating composition disclosed herein is
synonymous to waterborne and/or solventborne coating compositions
known in the art.
[0120] According to the present invention, the liquid coating
composition may comprise, for example, (a) a film forming polymer
having a reactive functional group; and (b) a curing agent that is
reactive with the functional group. In other examples, the liquid
coating may contain a film forming polymer that may react with
oxygen in the air or coalesce into a film with the evaporation of
water and/or solvents. These film forming mechanisms may require or
be accelerated by the application of heat or some type of radiation
such as Ultraviolet or Infrared. Examples of liquid coating
compositions that may be used in the present invention include the
SPECTRACRON.RTM. line of solventbased coating compositions, the
AQUACRON.RTM. line of waterbased coating compositions, and the
RAYCRON.RTM. line of UV cured coatings (all commercially available
from PPG Industries, Inc.).
[0121] Suitable film forming polymers that may be used in the
liquid coating composition of the present invention may comprise a
(poly)ester, an alkyd, a (poly)urethane, an isocyanurate, a
(poly)urea, a (poly)epoxy, an anhydride, an acrylic, a (poly)ether,
a (poly)sulfide, a (poly)amine, a (poly)amide, (poly)vinyl
chloride, (poly)olefin, (poly)vinylidene fluoride, (poly)siloxane,
or combinations thereof.
[0122] According to the present invention, the substrate that has
been contacted with the sealing composition may also be contacted
with a primer composition and/or a topcoat composition. The primer
coat may be, for examples, chromate-based primers and advanced
performance topcoats. According to the present invention, the
primer coat can be a conventional chromate based primer coat, such
as those available from PPG Industries, Inc. (product code
44GN072), or a chrome-free primer such as those available from PPG
(DESOPRIME CA7502, DESOPRIME CA7521, Deft 02GN083, Deft 02GN084).
Alternately, the primer coat can be a chromate-free primer coat,
such as the coating compositions described in U.S. patent
application Ser. No. 10/758,973, titled "CORROSION RESISTANT
COATINGS CONTAINING CARBON", and U.S. patent application Ser. Nos.
10/758,972, and 10/758,972, both titled "CORROSION RESISTANT
COATINGS", all of which are incorporated herein by reference, and
other chrome-free primers that are known in the art, and which can
pass the military requirement of MIL-PRF-85582 Class N or
MIL-PRF-23377 Class N may also be used with the current
invention.
[0123] As mentioned above, the substrate of the present invention
also may comprise a topcoat. As used herein, the term "topcoat"
refers to a mixture of binder(s) which can be an organic or
inorganic based polymer or a blend of polymers, typically at least
one pigment, can optionally contain at least one solvent or mixture
of solvents, and can optionally contain at least one curing agent.
A topcoat is typically the coating layer in a single or multi-layer
coating system whose outer surface is exposed to the atmosphere or
environment, and its inner surface is in contact with another
coating layer or polymeric substrate. Examples of suitable topcoats
include those conforming to MIL-PRF-85285D, such as those available
from PPG (Deft 03W127A and Deft 03GY292). According to the present
invention, the topcoat may be an advanced performance topcoat, such
as those available from PPG (Defthane.RTM. ELT.TM. 99GY001 and
99W009). However, other topcoats and advanced performance topcoats
can be used in the present invention as will be understood by those
of skill in the art with reference to this disclosure.
[0124] According to the present invention, the metal substrate also
may comprise a self-priming topcoat, or an enhanced self-priming
topcoat. The term "self-priming topcoat", also referred to as a
"direct to substrate" or "direct to metal" coating, refers to a
mixture of a binder(s), which can be an organic or inorganic based
polymer or blend of polymers, typically at least one pigment, can
optionally contain at least one solvent or mixture of solvents, and
can optionally contain at least one curing agent. The term
"enhanced self-priming topcoat", also referred to as an "enhanced
direct to substrate coating" refers to a mixture of functionalized
fluorinated binders, such as a fluoroethylene-alkyl vinyl ether in
whole or in part with other binder(s), which can be an organic or
inorganic based polymer or blend of polymers, typically at least
one pigment, can optionally contain at least one solvent or mixture
of solvents, and can optionally contain at least one curing agent.
Examples of self-priming topcoats include those that conform to
TT-P-2756A. Examples of self-priming topcoats include those
available from PPG (03W169 and 03GY369), and examples of enhanced
self-priming topcoats include Defthane.RTM. ELT.TM./ESPT and
product code number 97GY121, available from PPG. However, other
self-priming topcoats and enhanced self-priming topcoats can be
used in the coating system according to the present invention as
will be understood by those of skill in the art with reference to
this disclosure.
[0125] According to the present invention, the self-priming topcoat
and enhanced self-priming topcoat may be applied directly to the
sealed substrate. The self-priming topcoat and enhanced
self-priming topcoat can optionally be applied to an organic or
inorganic polymeric coating, such as a primer or paint film. The
self-priming topcoat layer and enhanced self-priming topcoat is
typically the coating layer in a single or multi-layer coating
system where the outer surface of the coating is exposed to the
atmosphere or environment, and the inner surface of the coating is
typically in contact with the substrate or optional polymer coating
or primer.
[0126] According to the present invention, the topcoat,
self-priming topcoat, and enhanced self-priming topcoat can be
applied to the sealed substrate, in either a wet or "not fully
cured" condition that dries or cures over time, that is, solvent
evaporates and/or there is a chemical reaction. The coatings can
dry or cure either naturally or by accelerated means for example,
an ultraviolet light cured system to form a film or "cured" paint.
The coatings can also be applied in a semi or fully cured state,
such as an adhesive.
[0127] In addition, a colorant and, if desired, various additives
such as surfactants, wetting agents or catalyst can be included in
the coating composition (electrodepositable, powder, or liquid). As
used herein, the term "colorant" means any substance that imparts
color and/or other opacity and/or other visual effect to the
composition. Example colorants include pigments, dyes and tints,
such as those used in the paint industry and/or listed in the Dry
Color Manufacturers Association (DCMA), as well as special effect
compositions.
[0128] In general, the colorant can be present in the coating
composition in any amount sufficient to impart the desired visual
and/or color effect. The colorant may comprise from 1 to 65 weight
percent, such as from 3 to 40 weight percent or 5 to 35 weight
percent, with weight percent based on the total weight of the
composition.
[0129] For purposes of the following detailed description, it is to
be understood that the invention may assume various alternative
variations and step sequences, except where expressly specified to
the contrary. Moreover, other than in any operating examples, or
where otherwise indicated, all numbers such as those expressing
values, amounts, percentages, ranges, subranges and fractions may
be read as if prefaced by the word "about," even if the term does
not expressly appear. Accordingly, unless indicated to the
contrary, the numerical parameters set forth in the following
specification and attached claims are approximations that may vary
depending upon the desired properties to be obtained by the present
invention. At the very least, and not as an attempt to limit the
application of the doctrine of equivalents to the scope of the
claims, each numerical parameter should at least be construed in
light of the number of reported significant digits and by applying
ordinary rounding techniques. Where a closed or open-ended
numerical range is described herein, all numbers, values, amounts,
percentages, subranges and fractions within or encompassed by the
numerical range are to be considered as being specifically included
in and belonging to the original disclosure of this application as
if these numbers, values, amounts, percentages, subranges and
fractions had been explicitly written out in their entirety.
[0130] Notwithstanding that the numerical ranges and parameters
setting forth the broad scope of the invention are approximations,
the numerical values set forth in the specific examples are
reported as precisely as possible. Any numerical value, however,
inherently contains certain errors necessarily resulting from the
standard variation found in their respective testing
measurements.
[0131] As used herein, unless indicated otherwise, a plural term
can encompass its singular counterpart and vice versa, unless
indicated otherwise. For example, although reference is made herein
to "a" conversion composition, "a" sealing composition, and "an"
oxidizing agent, a combination (i.e., a plurality) of these
components can be used. In addition, in this application, the use
of "or" means "and/or" unless specifically stated otherwise, even
though "and/or" may be explicitly used in certain instances.
[0132] As used herein, "including," "containing" and like terms are
understood in the context of this application to be synonymous with
"comprising" and are therefore open-ended and do not exclude the
presence of additional undescribed and/or unrecited elements,
materials, ingredients and/or method steps. As used herein,
"consisting of" is understood in the context of this application to
exclude the presence of any unspecified element, ingredient and/or
method step. As used herein, "consisting essentially of" is
understood in the context of this application to include the
specified elements, materials, ingredients and/or method steps "and
those that do not materially affect the basic and novel
characteristic(s)" of what is being described.
[0133] Unless otherwise disclosed herein, the term "substantially
free," when used with respect to the absence of a particular
material, means that such material, if present at all in a
composition, a bath containing the composition, and/or layers
formed from and comprising the composition, only is present in a
trace amount of 5 ppm or less based on a total weight of the
composition or layer(s), as the case may be, excluding any amount
of such material that may be present or derived as a result of
drag-in, substrate(s), and/or dissolution of equipment). Unless
otherwise disclosed herein, the term "essentially free," when used
with respect to the absence of a particular material, means that
such material, if present at all in a composition, a bath
containing the composition, and/or layers formed from and
comprising the composition, only is present in a trace amount of 1
ppm or less based on a total weight of the composition or layer(s),
as the case may be. Unless otherwise disclosed herein, the term
"completely free," when used with respect to the absence of a
particular material, means that such material, if present at all in
a composition, a bath containing the composition, and/or layers
formed from and comprising the composition, is absent from the
composition, the bath containing the composition, and/or layers
formed from and comprising same (i.e., the composition, bath
containing the composition, and/or layers formed from and
comprising the composition contain 0 ppm of such material).
[0134] As used herein, the terms "on," "onto," "applied on,"
"applied onto," "formed on," "deposited on," "deposited onto," mean
formed, overlaid, deposited, and/or provided on but not necessarily
in contact with the surface. For example, a coating layer "formed
over" a substrate does not preclude the presence of one or more
other intervening coating layers of the same or different
composition located between the formed coating layer and the
substrate.
[0135] As used herein, a "salt" refers to an ionic compound made up
of metal cations and non-metallic anions and having an overall
electrical charge of zero. Salts may be hydrated or anhydrous.
[0136] As used herein, "aqueous composition" refers to solution or
dispersion in a medium that comprises predominantly water. For
example, the aqueous medium may comprise water in an amount of more
than 50 wt. %, or more than 70 wt. % or more than 80 wt. % or more
than 90 wt. % or more than 95 wt. %, based on the total weight of
the medium. The aqueous medium may for example consist
substantially of water.
[0137] As used herein, "conversion composition" refers to a
composition that is capable of reacting with and chemically
altering the substrate surface and binding to it to form a film
that affords corrosion protection.
[0138] As used herein, "conversion bath" refers to an aqueous bath
containing the conversion composition and that may contain
components that are byproducts of the process of contacting a
substrate with the conversion composition.
[0139] As used herein, the term "conversion composition metal
cation(s)" refers to metal cations of a lanthanide series element,
a Group IIA metal, a Group IIIB metal, a Group IVB metal, a Group
VB metal, a Group VIB metal, a Group VIIB metal, and/or a Group XII
metal.
[0140] As used herein, a "sealing composition" refers to a
composition, e.g. a solution or dispersion, that affects a
substrate surface or a material deposited onto a substrate surface
in such a way as to alter the physical and/or chemical properties
of the substrate surface (i.e., the composition affords corrosion
protection).
[0141] As used herein, the term "Group IA metal" refers to an
element that is in Group IA of the CAS version of the Periodic
Table of the Elements as is shown, for example, in the Handbook of
Chemistry and Physics, 63.sup.rd edition (1983), corresponding to
Group 1 in the actual IUPAC numbering.
[0142] As used herein, the term "Group IA metal compound" refers to
compounds that include at least one element that is in Group IA of
the CAS version of the Periodic Table of the Elements.
[0143] As used herein, the term "Group IIIB metal" refers to
yttrium and scandium of the CAS version of the Periodic Table of
the Elements as is shown, for example, in the Handbook of Chemistry
and Physics, 63.sup.rd edition (1983), corresponding to Group 3 in
the actual IUPAC numbering. For clarity, "Group IIIB metal"
expressly excludes lanthanide series elements.
[0144] As used herein, the term "Group IIIB metal compound" refers
to compounds that include at least one element that is in group
IIIB of the CAS version of the Periodic Table of the Elements as
defined above.
[0145] As used herein, the term "Group IVB metal" refers to an
element that is in group IVB of the CAS version of the Periodic
Table of the Elements as is shown, for example, in the Handbook of
Chemistry and Physics, 63.sup.rd edition (1983), corresponding to
Group 4 in the actual IUPAC numbering.
[0146] As used herein, the term "Group IVB metal compound" refers
to compounds that include at least one element that is in Group IVB
of the CAS version of the Periodic Table of the Elements.
[0147] As used herein, the term "Group VB metal" refers to an
element that is in group VB of the CAS version of the Periodic
Table of the Elements as is shown, for example, in the Handbook of
Chemistry and Physics, 63.sup.rd edition (1983), corresponding to
Group 5 in the actual IUPAC numbering.
[0148] As used herein, the term "Group VB metal compound" refers to
compounds that include at least one element that is in Group VB of
the CAS version of the Periodic Table of the Elements.
[0149] As used herein, the term "Group VIB metal" refers to an
element that is in group VIB of the CAS version of the Periodic
Table of the Elements as is shown, for example, in the Handbook of
Chemistry and Physics, 63.sup.rd edition (1983), corresponding to
Group 6 in the actual IUPAC numbering.
[0150] As used herein, the term "Group VIB metal compound" refers
to compounds that include at least one element that is in Group VIB
of the CAS version of the Periodic Table of the Elements.
[0151] As used herein, the term "lanthanide series elements" refers
to elements 57-71 of the CAS version of the Periodic Table of the
Elements and includes elemental versions of the lanthanide series
elements. In embodiments, the lanthanide series elements may be
those which have both common oxidation states of +3 and +4,
referred to hereinafter as +3/+4 oxidation states.
[0152] As used herein, the term "lanthanide compound" refers to
compounds that include at least one of elements 57-71 of the CAS
version of the Periodic Table of the Elements.
[0153] As used herein, the term "halogen" refers to any of the
elements fluorine, chlorine, bromine, iodine, and astatine of the
CAS version of the Periodic Table of the Elements, corresponding to
Group VIIA of the periodic table.
[0154] As used herein, the term "halide" refers to compounds that
include at least one halogen.
[0155] As used herein, the term "aluminum," when used in reference
to a substrate, refers to substrates made of or comprising aluminum
and/or aluminum alloy, and clad aluminum substrates.
[0156] As used herein, the term "oxidizing agent," when used with
respect to a component of the conversion composition, refers to a
chemical which is capable of oxidizing at least one of: a metal
present in the substrate which is contacted by the conversion
composition, a lanthanide series element present in the conversion
composition, and/or a metal-complexing agent present in the
conversion composition. As used herein with respect to "oxidizing
agent," the phrase "capable of oxidizing" means capable of removing
electrons from an atom or a molecule present in the substrate or
the conversion composition, as the case may be, thereby decreasing
the number of electrons of such atom or molecule.
[0157] Pitting corrosion is the localized formation of corrosion by
which cavities or holes are produced in a substrate. The term
"pit," as used herein, refers to such cavities or holes resulting
from pitting corrosion and is characterized by (1) a rounded,
elongated or irregular appearance when viewed normal to the test
panel surface, (2) a "comet-tail", a line, or a "halo" (i.e., a
surface discoloration) emanating from the pitting cavity, and (3)
the presence of corrosion byproduct (e.g., white, grayish or black
granular, powdery or amorphous material) inside or immediately
around the pit. An observed surface cavity or hole must exhibit at
least two of the above characteristics to be considered a corrosion
pit. Surface cavities or holes that exhibit only one of these
characteristics may require additional analysis before being
classified as a corrosion pit. Visual inspection using a microscope
with 10.times. magnification is used to determine the presence of
corrosion byproducts when corrosion byproducts are not visible with
the unaided eye.
[0158] Unless otherwise disclosed herein, as used herein, the terms
"total composition weight", "total weight of a composition" or
similar terms refer to the total weight of all ingredients being
present in the respective composition including any carriers and
solvents.
[0159] In view of the foregoing description the present invention
thus relates in particular, without being limited thereto, to the
following Aspects 1-35: ASPECTS
[0160] 1. A method of treating a substrate comprising: contacting
at least a portion of the substrate surface with a sealing
composition comprising a lithium cation.
[0161] 2. The method of Aspect 1, wherein the sealing composition
is applied to provide a layer of the dried sealing composition
having a thickness of 5 nm to 550 nm.
[0162] 3. The method of either of the preceding Aspects, wherein
the lithium cation is present in the sealing composition as a
lithium salt.
[0163] 4. The method of any of the preceding Aspects, wherein the
lithium cation is present in the sealing composition in an amount
of 5 ppm to 5500 ppm (as lithium cation) based on total weight of
the sealing composition.
[0164] 6. The method of any of the preceding Aspects, wherein the
sealing composition further comprises a carbonate source, a
hydroxide source, or combinations thereof.
[0165] 7. The method of any of the preceding Aspects, wherein the
sealing composition further comprises a source of a Group IA metal
other than lithium, a Group VB metal source, a Group VIB metal
source, a corrosion inhibitor, an indicator compound, or
combinations thereof.
[0166] 8. The method of any of the preceding Aspects, wherein the
pH of the sealing composition is 9.5 to 12.5.
[0167] 9. The method of any of the preceding Aspects, wherein the
sealing composition is substantially free of fluoride, a Group IIA
metal cation, a cobalt ion, a vanadium ion, or combinations
thereof.
[0168] 10. The method of any of the preceding Aspects, wherein,
following the contacting with the sealing composition, the
substrate is not rinse with water prior to contacting at least a
portion of the substrate surface with subsequent treatment
compositions.
[0169] 11. The method of any of the preceding Aspects, wherein the
temperature of the sealing composition is 40 F to 160 F.
[0170] 12. The method of any of the preceding Aspects, wherein the
contacting with the sealing composition is for 1 second to 15
minutes.
[0171] 13. The method of any of the preceding Aspects further
comprising contacting at least a portion of the substrate surface
with a conversion composition comprising a lanthanide series
element cation, a Group IIIB metal cation, a Group IVB metal
cation, or combinations thereof; wherein the contacting with the
conversion composition occurs prior to the contacting with the
sealing composition.
[0172] 14. The method of Aspect 13, wherein the conversion
composition is applied to provide a film on the substrate resulting
in a level of the lanthanide series element cation, Group IIIB
metal cation, and/or Group IV metal cation on the treated substrate
surface of at least 100 counts greater than on a surface of a
substrate that does not have the film thereon as measured by X-ray
fluorescence (measured using X-Met 7500, Oxford Instruments;
operating parameters 60 second timed assay, 15 Kv, 45 .mu.A, filter
3, T(p)=1.51 .mu.s for lanthanides, Group IIIB metals, and Group
IVB metals except zirconium; operating parameters 60 second timed
assay, 40 Kv, 10 .mu.A, filter 4, T(p)=1.51 .mu.s for
zirconium).
[0173] 15. The method of any of Aspects 13 or 14, wherein the
lanthanide series element cation, Group IIIB metal cation, and/or
Group IVB metal cation comprises cerium, praseodymium, yttrium,
zirconium, titanium, or combinations thereof.
[0174] 16. The method of any of Aspects 13 to 15, wherein the
cations of the lanthanide series element, Group IIIB metal, and/or
Group IVB metal are present in the conversion composition in an
amount of 5 ppm to 25,000 ppm based on total weight of the
conversion composition.
[0175] 17. The method of any of Aspects 13 to 16, wherein the
conversion composition further comprises a halide, a nitrate, or
combinations thereof.
[0176] 18. The method of Aspect 17, wherein the halide is present
in the conversion composition in an amount of 9 ppm to 20,000 ppm
based on total weight of the conversion composition.
[0177] 19. The method of Aspect 17, wherein the nitrate is present
in the conversion composition in an amount of 2 ppm to 5000 ppm
based on total weight of the conversion composition.
[0178] 20. The method of any of Aspects 13 to 19, wherein the
conversion composition further comprises an oxidizing agent.
[0179] 21. The method of Aspect 20, wherein the oxidizing agent is
present in the conversion composition in an amount of 500 ppm to
3000 ppm based on total weight of the conversion composition.
[0180] 22. The method of any of Aspects 13 to 21, wherein the pH of
the conversion composition is 2.0 to 4.5.
[0181] 23. The method of any of Aspects 13 to 22, further
comprising heating the substrate at a temperature of 110 C to 232
C.
[0182] 24. The method of any of the preceding Aspects, wherein the
substrate comprises aluminum, aluminum alloys, or combinations
thereof.
[0183] 25. The method of any of the preceding Aspects, wherein the
substrate comprises an aluminum alloy comprising copper in an
amount of 1 percent by weight to 10 percent by weight.
[0184] 26. A system for treated a substrate comprising;
[0185] a conversion composition for treating at least a portion of
the substrate, comprising a lanthanide series cation, a Group IIIB
metal cation, a Group IVB metal cation, or combinations thereof;
and
[0186] a sealing composition for treating at least a portion of the
substrate, comprising a lithium cation.
[0187] 27. The system of Aspect 26, wherein the sealing composition
has a pH of 9.5 to 12.5.
[0188] 28. The system of Aspect 26 or 27, further comprising an
alkaline cleaning composition.
[0189] 29. A substrate obtainable by the method of any of Aspects 1
to 25.
[0190] 30. A substrate obtainable by the system of any of Aspects
26 to 28.
[0191] 31. The substrate of Aspect 29 or 30, wherein at least a
portion of the substrate surface is sanded.
[0192] 32. The substrate according to any of Aspects 29 to 31,
wherein substrate treated with the sealing composition has at least
a 50% reduction in the number of pits on the substrate surface
compared to a substrate not treated with the sealing composition
following 3 day exposure in neutral salt spray cabinet operated
according to ASTM B117.
[0193] 33. The substrate according to any of Aspects 29 to 32,
wherein the substrate treated with the conversion composition and
the sealing composition has at least a 50% reduction in the number
of pits on the substrate surface compared to a substrate treated
with the conversion composition or the sealing composition but not
the conversion composition and the sealing composition following 7
day exposure in neutral salt spray cabinet operated according to
ASTM B117.
[0194] 34. The substrate according to any of Aspects 29 to 33,
further comprising a primer layer.
[0195] 35. The substrate according to any of Aspects 29 to 34,
further comprising a topcoat layer.
[0196] Whereas particular features of the present invention have
been described above for purposes of illustration, it will be
evident to those skilled in the art that numerous variations of the
details of the coating composition, coating, and methods disclosed
herein may be made without departing from the scope in the appended
claims.
[0197] Illustrating the invention are the following examples that
are not to be considered as limiting the invention to their
details. All parts and percentages in the examples, as well as
throughout the specification, are by weight unless otherwise
indicated.
EXAMPLES
TABLE-US-00003 [0198] TABLE 3 Materials for Examples 1-5 Ridoline
298.sup.1 Henkel AG & Co. (Germany) Deoxidizer 6-16.sup.2
(6-16) Henkel AG & Co. Nitric acid cerium nitrate solution
ProChem Inc. (Rockford, IL) (65.37%
Ce(NO.sub.3).sub.3.cndot.6H.sub.2O) yttrium nitrate solution
ProChem Inc. (72.45% Y(NO.sub.3).sub.3.cndot.6H.sub.2O) cerium
chloride solution ProChem Inc. (32.2% as CeO.sub.2*) hydrogen
peroxide (30% H.sub.2O.sub.2) Alfa Aesar (Ward Hill, MA) sodium
hydroxide pellets, 98% Alfa Aesar sodium phosphate dodecahydrate,
97% Alfa Aesar polyvinylpyrrolidone (PVP), 8000 m.w. Alfa Aesar
Allantoin.sup.3, 98% Alfa Aesar 2,5-dimercapto-1,3,4-thiadiazole,
98% Acros Organics (Geel, Belgium) Carbowet GA100.sup.4, 100% Air
Products (Cleveland, OH) lithium carbonate, 98% Alfa Aesar sodium
vanadium oxide, 96% Ward Hill sodium molybdenum oxide dehydrate,
Alfa Aesar 98% .sup.1A non-silicated cleaner. .sup.2A deoxidizer.
.sup.3(2,5-dioxo-4-imidazolidinyl) urea. .sup.4A non-ionic
surfactant. *As per the supplier's analytical report, the
concentration of cerium in the cerium chloride solution is measured
as cerium oxide (CeO.sub.2).
TABLE-US-00004 TABLE 4 Equipment Technique Equipment Operating
parameters X-ray X-Met 7500, Operating Parameters for lanthanides,
Fluorescence Oxford Group IIIB metals and Group IVB metals (XRF)
Instruments except zirconium: Measurements 60 second timed assay
Voltage/current/filter: 15Kv_45.mu.A_filter 3 Dpp parameters: T(p)
= 1.5 .mu.s
TABLE-US-00005 TABLE 5A Example A INGREDIENTS % BY WEIGHT sodium
hydroxide pellets, 98% 1.6 sodium phosphate dodecahydrate, 97% 6.3
polyvinylpyrrolidone (PVP), 8000 m.w. 0.02 Allantoin, 98% 0.03
2,5-dimercapto-1,3,4-thiadiazole(DMTD), 98% 1.00 Carbowet GA100 4.1
deionized water 98.7
[0199] The ingredients used to prepare a solution of cleaner
Example A are provided in Table 5A. Sodium hydroxide and sodium
phosphate were completely dissolved in deionized water under mild
mechanical agitation using a stir plate (VWR, 7.times.7 CER
HOT/STIR). Next, the PVP was stirred in until dissolved, and then
Allantoin was added and stirred until dissolved, and then the DMTD
was added and stirred until dissolved. After the DMTD was
completely dissolved, Carbowet GA100 was stirred in under mild
mechanical agitation as above.
TABLE-US-00006 TABLE 5B Example B Ridoline 298 (R298), parts by
volume 100 tap water, parts by volume 900
[0200] The solution of Example B was prepared using the ingredients
shown in Table 5B, per manufacturer's instructions.
TABLE-US-00007 TABLE 6 Deoxidizer for Examples 4 and 5 Material
Example C Deoxidizer 6-16, parts by volume 100 nitric acid, parts
by volume 200 tap water, parts by volume 1700
[0201] Deoxidizer solutions of Example C was prepared using the
ingredients shown in Table 6, per manufacturers' instructions.
TABLE-US-00008 TABLE 7 Conversion Coating Compositions for Examples
1 and 3-8 Yttrium Cerium Cerium Hydrogen Nitrate Nitrate Chloride
Peroxide Deionized Solution Solution Solution Solution Water (g)
(g) (g) (g) (g) Example E 12.48 10.40 0.04 1.04 1953 Example F 0.00
0.00 84.0 5.20 1953
[0202] The ingredients used to prepare conversion coating
compositions E and F are shown in Table 7.
[0203] For the conversion coating composition of Example E, the
cerium nitrate, yttrium nitrate and cerium chloride solutions were
weighted into individual cups. Then using 500 grams of deionized
water, the solutions were transferred to a vessel containing 1000
grams of deionized water under mild agitation. The remaining 453
grams of water was added and the solution was stirred for 10
minutes to ensure uniformity before the hydrogen peroxide was
added. The final solution stirred for a minimum of 30 minutes
before use.
[0204] For the conversion coating composition of Example F,
solutions were prepared by adding the cerium chloride solution to
the full amount of deionized water under mild agitation. The
solution was stirred for 10 minutes to ensure uniformity before the
hydrogen peroxide was added. The final solution stirred for a
minimum of 30 minutes before use.
TABLE-US-00009 TABLE 8 Sealing Compositions of Examples 2-9
Material Example G Example H Example I lithium carbonate, grams
3.07 3.07 3.07 deionized water, grams 1996.93 1996.93 1996.93
sodium vanadium oxide, grams -- 1.67 -- sodium molybdenum oxide --
-- 1.67 dehydrate, grams
[0205] The sealing solution of Example G was prepared using the
ingredients shown in Table 8 by dissolving lithium carbonate in
deionized water under mild agitation using the stir plate as
described above.
[0206] The sealing solution of Example H was prepared using the
ingredients shown in Table 8 by dissolving lithium carbonate in
deionized water under mild agitation using the stir plate as
described above. Next, the sodium vanadium oxide was added and
dissolved under mild agitation as described above.
[0207] The sealing solution of Example I was prepared using the
ingredients shown in Table 8 by dissolving lithium carbonate in
deionized water under mild agitation using the stir plate as
described above. Next, the sodium molybdenum oxide dehydrate was
added and dissolved under mild agitation as described above.
Example 1
[0208] Aluminum 2024T3 bare substrate (Priority Metals, Orange
County, Calif.) measuring 3''.times.5''.times.0.032'' was
hand-wiped with methyl ethyl ketone (100%) and a disposable cloth
and allowed to air dry prior to chemical cleaning. The panel was
immersed in the cleaner solution of Example A for 3.5 minutes at
ambient temperature with intermittent agitation. The panel was then
immersed in two subsequent deionized water rinses for two minutes
each, both at ambient temperature with intermittent agitation.
After the second rinse, the panel received a cascading deionized
water rinse for 10 seconds. The panel was then immersed in the
conversion coating composition of Example E for 5 minutes at
ambient temperature and without agitation. After the conversion
coating, the panel received an immersion rinse in deionized water
for 1 minute at ambient temperature with intermittent agitation
followed by a 10 second cascading deionized water rinse. The panel
was air dried at ambient conditions overnight before testing.
Example 2
[0209] Aluminum 2024T3 bare substrate measuring
3''.times.5''.times.0.032'' was hand-wiped with methyl ethyl ketone
(100%) and a disposable cloth and allowed to air dry prior to
chemical cleaning. The panel was immersed in the cleaner solution
of Example A for 3.5 minutes at ambient temperature with
intermittent agitation. The panel was then immersed in two
subsequent deionized water rinses for two minutes each, both at
ambient temperature with intermittent agitation. After the second
rinse, the panel received a cascading deionized water rinse for 10
seconds. The panel was then immersed in the seal solution of
Example G for 2 minutes at ambient temperature with intermittent
agitation. The panel was air dried at ambient conditions overnight
before testing.
Example 3
[0210] Aluminum 2024T3 bare substrate measuring
3''.times.5''.times.0.032'' was hand-wiped with methyl ethyl ketone
(100%) and a disposable cloth and allowed to air dry prior to
chemical cleaning. The panel was immersed in the cleaner solution
of Example A for 3.5 minutes at ambient temperature with
intermittent agitation. The panel was then immersed in two
subsequent deionized water rinses for two minutes each, both at
ambient temperature with intermittent agitation. After the second
rinse, the panel received a cascading deionized water rinse for 10
seconds. The panel was then immersed in the conversion coating
composition of Example E for 5 minutes at ambient temperature and
without agitation. After the conversion coating, the panel received
an immersion rinse in deionized water for 1 minute at ambient
temperature with intermittent agitation followed by a 10 second
cascading deionized water rinse. The panel was then immersed in the
seal solution of Example G for 2 minutes at ambient temperature
with intermittent agitation. The panel was air dried at ambient
conditions overnight before testing.
Example 4
[0211] Aluminum 2024T3 bare substrate measuring
3''.times.5''.times.0.032'' was hand-wiped with methyl ethyl ketone
(100%) and a disposable cloth and allowed to air dry prior to
chemical cleaning. The panel was immersed in the cleaner solution
of Example B for 2 minutes at 55.degree. C. with mild agitation.
The panel was then immersed in a tap water rinse for one minute at
ambient temperature with mild agitation followed by a 10 second
cascading tap water rinse. The panel was immersed in a deoxidizing
solution of Example C for 1.5 minutes at ambient temperature
followed by a one minute immersion rinse in tap water at ambient
temperature and mild agitation followed by a 10 second cascading
rinse. The panel was then immersed in the conversion coating
composition of Example E for 5 minutes at ambient temperature and
without agitation. After the conversion coating, the panel received
an immersion rinse in deionized water for 1 minute at ambient
temperature with intermittent agitation followed by a 10 second
cascading deionized water rinse. The panel was then immersed in the
seal solution of Example G for 2 minutes at ambient temperature
with intermittent agitation. The panel was air dried at ambient
conditions overnight before testing.
Example 5
[0212] Aluminum 2024T3 bare substrate measuring
3''.times.5''.times.0.032'' was hand-wiped with methyl ethyl ketone
(100%) and a disposable cloth and allowed to air dry prior to
chemical cleaning. The panel was immersed in the cleaner solution
of Example B for 2 minutes at 55.degree. C. with mild agitation.
The panel was then immersed in a tap water rinse for one minute at
ambient temperature with mild agitation followed by a 10 second
cascading tap water rinse. The panel was immersed in a deoxidizing
solution of Example C for 1.5 minutes at ambient temperature
followed by a one minute immersion rinse in tap water at ambient
temperature and mild agitation followed by a 10 second cascading
rinse. The panel was then immersed in the conversion coating
composition of Example F for 7 minutes at ambient temperature and
without agitation. After the conversion coating, the panel received
an immersion rinse in deionized water for 1 minute at ambient
temperature with intermittent agitation followed by a 10 second
cascading deionized water rinse. The panel was then immersed in the
seal solution of Example G for 2 minutes at ambient temperature
with intermittent agitation. The panel was air dried at ambient
conditions overnight before testing.
Example 6
[0213] A 3'.times.10''.times.0.032'' panel of Al 2024-T3 was
solvent wiped on both sides with Methyl Ethyl Ketone using a
lint-free paper towel until the surface was visually free from
grease and oil. The panel was then immersed in the cleaner solution
of Example A for 7 minutes at ambient temperature. Next, the panel
was then rinsed using a de-ionized water spray rinse for two
minutes followed by a de-ionized water immersion rinse for two
minutes. The panel was then immersed in the conversion coating
composition of Example E for 5 minutes at ambient temperature. The
panel was then immersed in de-ionized water for two minutes,
followed by a second de-ionized water rinse for two minutes. The
metal substrate was then immersed in the sealing composition of
Example G for two minutes. The panel was allowed to air dry at
ambient conditions prior to testing.
Example 7
[0214] A 3''.times.10''.times.0.032'' panel of Al 2024-T3 was
solvent wiped on both sides with Methyl Ethyl Ketone using a
lint-free paper towel until the surface was visually free from
grease and oil. The panel was then immersed in the cleaner solution
of Example A for 7 minutes at ambient temperature. Next, the panel
was then rinsed using a de-ionized water spray rinse for two
minutes followed by a de-ionized water immersion rinse for two
minutes. The panel was then immersed in the conversion coating
composition of Example E for 5 minutes at ambient temperature. The
panel was then immersed in de-ionized water for two minutes,
followed by a second de-ionized water rinse for two minutes. The
metal substrate was then immersed in the sealing composition of
Example H for 2 minutes. The panel was allowed to air dry at
ambient conditions prior to testing.
Example 8
[0215] A 3''.times.10''.times.0.032'' panel of Al 2024-T3 was
solvent wiped on both sides with Methyl Ethyl Ketone using a
lint-free paper towel until the surface was visually free from
grease and oil. The panel was then immersed in the cleaner solution
of Example A for 7 minutes. Next, the panel was rinsed using a
de-ionized water spray rinse for two minutes followed by a
de-ionized water immersion rinse for two minutes. The panel was
then immersed in the conversion coating composition of Example E
for 5 minutes at ambient temperature. The panel was then immersed
in de-ionized water for two minutes, followed by a second
de-ionized water rinse for two minutes. The metal substrate was
then immersed in the sealing composition of Example I described
above for 2 minutes. The panel was allowed to air dry at ambient
conditions prior to testing.
Evaluation of the Panels of Examples 1-8
[0216] The panels from Examples 1-5 were analyzed for deposition of
lanthanide using X-ray fluorescence (measured using X-Met 7500,
Oxford Instruments; operating parameters 60 second timed assay, 15
Kv, 45 .mu.A, filter 3, T(p)=1.5 .mu.s). Data are reported in Table
9.
[0217] The panels from Examples 1-5 were evaluated for corrosion
resistance by placing each panel in a 7 day exposure neutral salt
spray cabinet operated according to ASTM B117. Corrosion
performance was evaluated by counting the number of pits visible to
the naked eye on the panels. Data are reported in Table 9.
[0218] The panels from Examples 6-8 were evaluated for corrosion
resistance by placing each panels in a 3 day exposure neutral salt
spray cabinet operated according to ASTM B117. Corrosion
performance was evaluated using the rating scale shown in Table 10.
Data are reported in Table 9.
TABLE-US-00010 TABLE 9 Corrosion performance and XRF readings
Conversion Sealing Clean/Deox Composition Composition Salt Spray
XRF Reading 7 days 1 Example A Example E None 100+ pits 662 (Ce) 2
Example A None Example G 100+ pits 299 (Ce) - baseline 3 Example A
Example E Example G 0 pits 768 (Ce) 4 Example B/C Example E Example
G 100+ pits 313 (Ce) 5 Example B/C Example F Example G 3 pits 1478
(Ce) 3 days 6 Example A Example E Example G 8 (rating) n/a 7
Example A Example E Example H 9 (rating) n/a 8 Example A Example E
Example I 10 (rating) n/a
TABLE-US-00011 TABLE 10 Rating Scale for Salt Spray Rating
Description 10 identical to how they went in to test/no corrosion 9
passes with no "countable" pits (if there is a pit, it's either
from an edge, scratch, pre-existing, etc.) 8 .ltoreq.five pits with
corrosion salt tails 7 .gtoreq.5 pits with tails and .ltoreq.15
pits total 6 >15 pits total and .ltoreq.40 pits total 5 30%
surface corrosion 4 50% surface corrosion 3 70% surface corrosion 2
85% surface corrosion 1 100% surface corrosion
[0219] The data shown in Table 9 demonstrate that the combination
contacting a substrate surface with a lanthanide-containing
conversion composition and a lithium-containing sealing composition
that includes either a molybdenum salt or a vanadium salt further
reduced the level of pitting on the substrate surface following 3
day exposure in neutral salt spray cabinet operated according to
ASTM B117 compared to a substrate surface that has been contacted
with the conversion composition and a sealing composition that does
not include the molybdenum salt or the vanadium salt.
[0220] The data shown in Table 9 also demonstrate that contacting
an anodized substrate with the lithium-containing sealing
composition resulted in a treated substrate which had a salt spray
rating of 8 following 7 day exposure in neutral salt spray cabinet
operated according to ASTM B117.
[0221] The data shown in Table 9 also demonstrate that the
combination of a film formed from a lanthanide-containing
conversion composition with a layer formed from a
lithium-containing sealing composition results in at least a 50%
reduction in the number of pits on the substrate surface compared
to a substrate surface that has the conversion composition film or
the sealing composition layer but not both following 7 day exposure
in neutral salt spray cabinet operated according to ASTM B117.
Examples AA Through MM
TABLE-US-00012 [0222] TABLE 11 Additional Materials for Examples
BB, FF and II through LL Yttrium Chloride, 99.9% Alfa Aesar
Potassium Hexafluorozirconate, 99% Alfa Aesar Potassium
Hexafluorotitanate, 97% Alfa Aesar
TABLE-US-00013 TABLE 12 Additional Conversion Coating Compositions
for Examples BB through FF Yttrium Yttrium Cerium Cerium Hydrogen
Nitrate Chloride Nitrate Chloride Peroxide Deionized Solution (g)
Solid (g) Solution (g) Solution (g) Solution (g) Water (g) Example
J -- -- 25.08 .04 1.01 1874.88 Example K 19.97 0.015 -- -- 1.01
1880.03
TABLE-US-00014 TABLE 13 Additional Conversion Coating Compositions
for Examples JJ through MM Potassium Potassium Hydrogen Hexafluoro-
Hexafluoro- Peroxide Deionized zirconate titanate Solution Water
(g) (g) (g) (g) Example L 2.38 -- 1.19 1897.60 Example M -- 2.38
1.00 1897.60
Preparation of Conversion Compositions
[0223] The ingredients used to prepare conversion coating
compositions J and K are shown in Table 12.
[0224] For the conversion coating composition of Example J, the
cerium nitrate and cerium chloride solutions were weighted into
individual cups. Then using 500 grams of deionized water, the
solutions were transferred to a vessel containing 1000 grams of
deionized water under mild agitation. The remaining 374.88 grams of
water were added and the solution was stirred for 10 minutes to
ensure uniformity before the hydrogen peroxide was added. The final
solution stirred for a minimum of 30 minutes before use.
[0225] For the conversion coating composition of Example K, the
yttrium nitrate and yttrium chloride solutions were weighted into
individual cups. Then using 500 grams of deionized water, the
solutions were transferred to a vessel containing 1000 grams of
deionized water under mild agitation. The remaining 380.03 grams of
water were added and the solution was stirred for 10 minutes to
ensure uniformity before the hydrogen peroxide was added. The final
solution stirred for a minimum of 30 minutes before use.
[0226] For the conversion coating compositions of Examples II
through LL, the entire amount of deionized water was weighed into a
container. The zirconium salt was measured into a separate cup then
transferred into the vessel containing the deionized water while
under moderate stirring. The solution continued to stir for 15
minutes to allow the entire amount of salt to dissolve. This exact
process was used to prepare the titanium solution.
Example AAA (Comparative)
[0227] Aluminum 2024T3 bare substrate (Priority Metals, Orange
County, Calif.) measuring 3''.times.5''.times.0.032'' was
hand-wiped with methyl ethyl ketone (100%) and a disposable cloth
and allowed to air dry prior to chemical cleaning. The panel was
immersed in the cleaner solution of Example A for 3.5 minutes at
ambient temperature with intermittent agitation. The panel was then
immersed in two subsequent deionized water rinses for two minutes
each, both at ambient temperature with intermittent agitation.
After the second rinse, the panel was air dried at ambient
conditions overnight before testing.
[0228] The panel was placed in 3 day and 7 day exposure in neutral
salt spray cabinet operated according to ASTM B117. Corrosion
performance was evaluated by counting the number of pits visible to
the naked eye on the panels. Data are reported in Table 14.
Example AA
[0229] Aluminum 2024T3 bare substrate (Priority Metals, Orange
County, Calif.) measuring 3''.times.5''.times.0.032'' was
hand-wiped with methyl ethyl ketone (100%) and a disposable cloth
and allowed to air dry prior to chemical cleaning. The panel was
immersed in the cleaner solution of Example A for 3.5 minutes at
ambient temperature with intermittent agitation. The panel was then
immersed in two subsequent deionized water rinses for two minutes
each, both at ambient temperature with intermittent agitation.
After the second rinse, the panel received a cascading deionized
water rinse for 10 seconds. The panel was then immersed in the seal
solution of Example G for 2 minutes at ambient temperature with
intermittent agitation. The panel was air dried at ambient
conditions overnight before testing.
Example BB
[0230] Aluminum 2024T3 bare substrate (Priority Metals, Orange
County, Calif.) measuring 3''.times.5''.times.0.032'' was
hand-wiped with methyl ethyl ketone (100%) and a disposable cloth
and allowed to air dry prior to chemical cleaning. The panel was
immersed in the cleaner solution of Example A for 3.5 minutes at
ambient temperature with intermittent agitation. The panel was then
immersed in two subsequent deionized water rinses for two minutes
each, both at ambient temperature with intermittent agitation.
After the second rinse, the panel received a cascading deionized
water rinse for 10 seconds. The panel was then immersed in the
conversion coating of Example J for 5 minutes at ambient
temperature and without agitation. After the conversion coating,
the panel received an immersion rinse in deionized water for 2
minutes at ambient temperature with intermittent agitation followed
by a 10 second cascading deionized water rinse. The panel was air
dried at ambient conditions overnight before testing.
Example CC
[0231] Aluminum 2024T3 bare substrate (Priority Metals, Orange
County, Calif.) measuring 3''.times.5''.times.0.032'' was
hand-wiped with methyl ethyl ketone (100%) and a disposable cloth
and allowed to air dry prior to chemical cleaning. The panel was
immersed in the cleaner solution of Example A for 3.5 minutes at
ambient temperature with intermittent agitation. The panel was then
immersed in two subsequent deionized water rinses for two minutes
each, both at ambient temperature with intermittent agitation.
After the second rinse, the panel received a cascading deionized
water rinse for 10 seconds. The panel was then immersed in the
conversion coating of Example K for 5 minutes at ambient
temperature and without agitation. After the conversion coating,
the panel received an immersion rinse in deionized water for 2
minutes at ambient temperature with intermittent agitation followed
by a 10 second cascading deionized water rinse. The panel was air
dried at ambient conditions overnight before testing.
Example DD
[0232] Aluminum 2024T3 bare substrate measuring
3''.times.5''.times.0.032'' was hand-wiped with methyl ethyl ketone
(100%) and a disposable cloth and allowed to air dry prior to
chemical cleaning. The panel was immersed in the cleaner solution
of Example B for 2 minutes at 55.degree. C. with mild agitation.
The panel was then immersed in a tap water rinse for one minute at
ambient temperature with mild agitation followed by a 10 second
cascading tap water rinse. The panel was immersed in a deoxidizing
solution of Example C for 1.5 minutes at ambient temperature
followed by a one minute immersion rinse in tap water at ambient
temperature and mild agitation followed by a 10 second cascading
rinse. The panel was then immersed in the conversion coating of
Example J for 5 minutes at ambient temperature and without
agitation. After the conversion coating, the panel received an
immersion rinse in deionized water for 2 minutes at ambient
temperature with intermittent agitation followed by a 10 second
cascading deionized water rinse. The panel was then immersed in the
seal solution of Example G for 2 minutes at ambient temperature
with intermittent agitation. The panel was air dried at ambient
conditions overnight before testing.
Example EE
[0233] Aluminum 2024T3 bare substrate measuring
3''.times.5''.times.0.032'' was hand-wiped with methyl ethyl ketone
(100%) and a disposable cloth and allowed to air dry prior to
chemical cleaning. The panel was immersed in the cleaner solution
of Example A for 3.5 minutes at ambient temperature with
intermittent agitation. The panel was then immersed in two
subsequent deionized water rinses for two minutes each, both at
ambient temperature with intermittent agitation. After the second
rinse, the panel received a cascading deionized water rinse for 10
seconds. The panel was then immersed in the conversion coating of
Example J for 5 minutes at ambient temperature and without
agitation. After the conversion coating, the panel received an
immersion rinse in deionized water for 2 minutes at ambient
temperature with intermittent agitation followed by a 10 second
cascading deionized water rinse. The panel was then immersed in the
seal solution of Example G for 2 minutes at ambient temperature
with intermittent agitation. The panel was air dried at ambient
conditions overnight before testing.
Example FF
[0234] Aluminum 2024T3 bare substrate measuring
3''.times.5''.times.0.032'' was hand-wiped with methyl ethyl ketone
(100%) and a disposable cloth and allowed to air dry prior to
chemical cleaning. The panel was immersed in the cleaner solution
of Example A for 3.5 minutes at ambient temperature with
intermittent agitation. The panel was then immersed in two
subsequent deionized water rinses for two minutes each, both at
ambient temperature with intermittent agitation. After the second
rinse, the panel received a cascading deionized water rinse for 10
seconds. The panel was then immersed in the conversion coating of
Example K for 5 minutes at ambient temperature and without
agitation. After the conversion coating, the panel received an
immersion rinse in deionized water for 2 minutes at ambient
temperature with intermittent agitation followed by a 10 second
cascading deionized water rinse. The panel was then immersed in the
seal solution of Example G for 2 minutes at ambient temperature
with intermittent agitation. The panel was air dried at ambient
conditions overnight before testing.
Example GG
[0235] Aluminum 2024T3 bare substrate measuring
3''.times.5''.times.0.032'' was hand-wiped with methyl ethyl ketone
(100%) and a disposable cloth and allowed to air dry prior to
chemical cleaning. The panel was immersed in the cleaner solution
of Example A for 3.5 minutes at ambient temperature with
intermittent agitation. The panel was then immersed in two
subsequent deionized water rinses for two minutes each, both at
ambient temperature with intermittent agitation. After the second
rinse, the panel received a cascading deionized water rinse for 10
seconds. The panel was then immersed in the conversion coating of
Example E for 5 minutes at ambient temperature and without
agitation. After the conversion coating, the panel received an
immersion rinse in deionized water for 2 minutes at ambient
temperature with intermittent agitation followed by a 10 second
cascading deionized water rinse. The panel was then immersed in the
seal solution of Example G for 2 minutes at ambient temperature
with intermittent agitation. The panel was air dried at ambient
conditions overnight before testing.
Example HH
[0236] Aluminum 2024T3 bare substrate measuring
3''.times.5''.times.0.032'' was hand-wiped with methyl ethyl ketone
(100%) and a disposable cloth and allowed to air dry prior to
chemical cleaning. The panel was immersed in the cleaner solution
of Example B for 2 minutes at 55.degree. C. with mild agitation.
The panel was then immersed in a tap water rinse for one minute at
ambient temperature with mild agitation followed by a 10 second
cascading tap water rinse. The panel was immersed in a deoxidizing
solution of Example C for 1.5 minutes at ambient temperature
followed by a one minute immersion rinse in tap water at ambient
temperature and mild agitation followed by a 10 second cascading
rinse. The panel was then immersed in the conversion coating of
Example F for 5 minutes at ambient temperature and without
agitation. After the conversion coating, the panel received an
immersion rinse in deionized water for 2 minutes at ambient
temperature with intermittent agitation followed by a 10 second
cascading deionized water rinse. The panel was then immersed in the
seal solution of Example G for 2 minutes at ambient temperature
with intermittent agitation. The panel was air dried at ambient
conditions overnight before testing.
Example II
[0237] Aluminum 2024T3 bare substrate measuring
3''.times.5''.times.0.032'' was hand-wiped with methyl ethyl ketone
(100%) and a disposable cloth and allowed to air dry prior to
chemical cleaning. The panel was immersed in the cleaner solution
of Example A for 3.5 minutes at ambient temperature with
intermittent agitation. The panel was then immersed in an ambient
deionized water rinse for 5 seconds followed by an ambient
deionized water immersion rinse for 2 minutes with intermittent
agitation. After the second rinse, the panel received a cascading
deionized water rinse for 10 seconds. The panel was then immersed
in the seal solution of Example G for 2 minutes at ambient
temperature with intermittent agitation. The panel was air dried at
ambient conditions overnight before testing.
Example JJ
[0238] Aluminum 2024T3 bare substrate measuring
3''.times.5''.times.0.032'' was hand-wiped with methyl ethyl ketone
(100%) and a disposable cloth and allowed to air dry prior to
chemical cleaning. The panel was immersed in the cleaner solution
of Example A for 3.5 minutes at ambient temperature with
intermittent agitation. The panel was then immersed in an ambient
deionized water rinse for 5 seconds followed by an ambient
deionized water immersion rinse for 2 minutes with intermittent
agitation. After the second rinse, the panel received a cascading
deionized water rinse for 10 seconds. The panel was then immersed
in the conversion coating of Example L for 1 minute at ambient
temperature and without agitation. After the conversion coating,
the panel received an immersion rinse in deionized water for 2
minutes at ambient temperature with intermittent agitation followed
by a 10 second cascading deionized water rinse. The panel was air
dried at ambient conditions overnight before testing.
Example KK
[0239] Aluminum 2024T3 bare substrate measuring
3''.times.5''.times.0.032'' was hand-wiped with methyl ethyl ketone
(100%) and a disposable cloth and allowed to air dry prior to
chemical cleaning. The panel was immersed in the cleaner solution
of Example A for 3.5 minutes at ambient temperature with
intermittent agitation. The panel was then immersed in an ambient
deionized water rinse for 5 seconds followed by an ambient
deionized water immersion rinse for 2 minutes with intermittent
agitation. After the second rinse, the panel received a cascading
deionized water rinse for 10 seconds. The panel was then immersed
in the conversion coating of Example L for 1 minute at ambient
temperature and without agitation. After the conversion coating,
the panel received an immersion rinse in deionized water for 2
minutes at ambient temperature with intermittent agitation followed
by a 10 second cascading deionized water rinse. The panel was then
immersed in the seal solution of Example G for 2 minutes at ambient
temperature with intermittent agitation. The panel was air dried at
ambient conditions overnight before testing.
Example LL
[0240] Aluminum 2024T3 bare substrate measuring
3''.times.5''.times.0.032'' was hand-wiped with methyl ethyl ketone
(100%) and a disposable cloth and allowed to air dry prior to
chemical cleaning. The panel was immersed in the cleaner solution
of Example A for 3.5 minutes at ambient temperature with
intermittent agitation. The panel was then immersed in an ambient
deionized water rinse for 5 seconds followed by an ambient
deionized water immersion rinse for 2 minutes with intermittent
agitation. After the second rinse, the panel received a cascading
deionized water rinse for 10 seconds. The panel was then immersed
in the conversion coating of Example M for 1 minute at ambient
temperature and without agitation. After the conversion coating,
the panel received an immersion rinse in deionized water for 2
minutes at ambient temperature with intermittent agitation followed
by a 10 second cascading deionized water rinse. The panel was air
dried at ambient conditions overnight before testing.
Example MM
[0241] Aluminum 2024T3 bare substrate measuring
3''.times.5''.times.0.032'' was hand-wiped with methyl ethyl ketone
(100%) and a disposable cloth and allowed to air dry prior to
chemical cleaning. The panel was immersed in the cleaner solution
of Example A for 3.5 minutes at ambient temperature with
intermittent agitation. The panel was then immersed in an ambient
deionized water rinse for 5 seconds followed by an ambient
deionized water immersion rinse for 2 minutes with intermittent
agitation. After the second rinse, the panel received a cascading
deionized water rinse for 10 seconds. The panel was then immersed
in the conversion coating of Example M for 1 minute at ambient
temperature and without agitation. After the conversion coating,
the panel received an immersion rinse in deionized water for 2
minutes at ambient temperature with intermittent agitation followed
by a 10 second cascading deionized water rinse. The panel was then
immersed in the seal solution of Example G for 2 minutes at ambient
temperature with intermittent agitation. The panel was air dried at
ambient conditions overnight before testing.
Evaluation of the Panels of Examples AA Through MM
[0242] The panels of Examples AA through MM were analyzed for
deposition of lanthanide using X-ray fluorescence (measured using
X-Met 7500, Oxford Instruments; operating parameters 60 second
timed assay, 15 Kv, 45 .mu.A, filter 3, T(p)=1.5 .mu.s). Data are
reported in Table 14.
[0243] For each of Examples AA through MM, one panel was placed in
a 3 day exposure and one panel was placed in a 7 day exposure in a
neutral salt spray cabinet operated according to ASTM B117.
Corrosion performance was evaluated by counting the number of pits
visible to the naked eye on the panels. Data are reported in Table
14.
TABLE-US-00015 TABLE 4 Corrosion performance and XRF readings
(Example AAA and AA-MM) Conversion Sealing Salt Spray XRF Reading
Clean/Deox Composition Composition (No of Pits) Ce Y Zr Ti 7 days
AAA Example A none none 100+ 436 322 -- -- (baseline) (baseline) AA
Example A none Example G 79 454 345 -- -- BB Example A Example J
none 100+ 850 -- -- -- CC Example A Example K none 100+ -- 418 --
-- DD Example B/C Example J Example G 59 444 -- -- -- EE Example A
Example J Example G 8 837 -- -- -- FF Example A Example K Example G
53 -- 429 -- -- GG Example A Example E Example G 7 845 -- -- -- HH
Example B/C Example F Example G 36 909 -- -- -- Example A none none
-- -- -- 630 331 (baseline) (baseline) II Example A none Example G
100+ -- -- 575 331 JJ Example A Example L none 100+ -- -- 670 -- KK
Example A Example L Example G 20 -- -- 697 -- LL Example A Example
M none 100+ -- -- -- 607 MM Example A Example M Example G 24 -- --
-- 904 3 days AA Example A none Example G 58 850 -- -- -- BB
Example A Example J none 100+ -- 418 -- -- CC Example A Example K
none 100+ 444 -- -- -- DD Example B/C Example J Example G 19 837 --
-- -- EE Example A Example J Example G 0 -- 429 -- -- FF Example A
Example K Example G 20 845 -- -- -- GG Example A Example E Example
G 0 909 -- -- -- HH Example B/C Example F Example G 4 -- -- 575 331
II Example A None Example G 100+ -- -- 670 -- JJ Example A Example
L None 100+ -- -- 697 -- KK Example A Example L Example G 9 -- --
-- 607 LL Example A Example M None 100+ -- -- -- 904 MM Example A
Example M Example G 15
[0244] The data in Table 14 above demonstrate that, when compared
to a metal substrate that was not treated in accordance with the
method of the present invention (Example AAA), a metal substrate
that was treated with the sealing composition via the method of the
present invention (Example AA) provided a reduction in the amount
of corrosion on the treated substrate after exposure to neutral
salt spray for 7 days. Evidence of the reduced corrosion is
demonstrated by the occurrence of only 79 pits for Example AA
versus 100+ pits for Example AAA.
[0245] In Example DD, wherein the substrate was first contacted
with a conversion coating comprising a lanthanide series element
(cerium) and subsequently contacted with a sealing solution
comprising a lithium salt, demonstrated a reduced number of
corrosion pits after both 3 days and 7 days exposure to neutral
salt spray in comparison to both Examples AA (substrate only
contacted with the sealing solution) and BB (substrate only
contacted with the lanthanide containing conversion coating).
[0246] In Example EE, wherein the substrate was first contacted
with a conversion coating comprising a lanthanide series element
(cerium) and subsequently contacted with a sealing solution
comprising a lithium salt, demonstrated greater than a 50%
reduction in the number of corrosion pits after both 3 days and 7
days exposure to neutral salt spray in comparison to both Examples
AA (substrate only contacted with the sealing solution) and BB
(substrate only contacted with the lanthanide containing conversion
coating). Additionally, the number of pits were further reduced
relative to Example DD and the detectable level of cerium on the
substrate was measurably greater than that measured for Example
DD.
[0247] Example FF, wherein the substrate was first contacted with a
conversion coating comprising a lanthanide series element (yttrium)
and subsequently contacted with a sealing solution comprising a
lithium salt, demonstrated greater than a 50% reduction in the
number of corrosion pits after both 3 days and 7 days exposure to
neutral salt spray in comparison to both Examples AA (substrate
only contacted with the sealing solution) and CC (substrate only
contacted with the lanthanide containing conversion coating).
[0248] Example GG, wherein the substrate was first contacted with a
conversion coating comprising a lanthanide series element (both
cerium and yttrium) and subsequently contacted with a sealing
solution comprising a lithium salt, demonstrated a reduced number
of corrosion pits after 7 days exposure to neutral salt spray in
comparison to both Example AA (substrate only contacted with the
sealing solution) and Example 1 (substrate only contacted with the
lanthanide containing conversion coating).
[0249] Example HH, wherein the substrate was first contacted with a
conversion coating comprising a lanthanide series element (cerium)
and subsequently contacted with a sealing solution comprising a
lithium salt, demonstrated a reduced number of corrosion pits after
7 days exposure to neutral salt spray in comparison to both Example
AA (substrate only contacted with the sealing solution) and Example
4 (substrate only contacted with the lanthanide containing
conversion coating). Additionally, the number of pits were further
reduced relative to Example DD and the detectable level of cerium
on the substrate was measurably greater than that measured for
Example DD.
[0250] Example KK, wherein the substrate was first contacted with a
conversion coating comprising a Group IVB series element
(zirconium) and subsequently contacted with a sealing solution
comprising a lithium salt, demonstrated a reduced number of
corrosion pits after 7 days exposure to neutral salt spray in
comparison to both Examples II (substrate only contacted with the
sealing solution) and JJ (substrate only contacted with the Group
IVB containing conversion coating).
[0251] Example MM, wherein the substrate was first contacted with a
conversion coating comprising a Group IVB series element (titanium)
and subsequently contacted with a sealing solution comprising a
lithium salt, demonstrated a reduced number of corrosion pits after
7 days exposure to neutral salt spray in comparison to both
Examples II (substrate only contacted with the sealing solution)
and LL (substrate only contacted with the Group IVB containing
conversion coating).
Example NN
[0252] Aluminum 6111 panels (from ACT Test Panels, LLC) were cut to
4''.times.6'' sample size. The bottom 3'' of the panels were sanded
with P320 grit silicon carbide paper (available from 3M) on a 6''
random orbital palm sander (Advanced Tool Design Model-ATD-2088).
Half-sanding the panel surface served to determine any corrosion
performance difference between as-milled (unsanded) and sanded
substrates. Surface sanding or abrasion is conducted in the field
to promote adhesion of subsequent paint applications.
[0253] Each of the half-sanded 6111 aluminum panels were spray
cleaned with standard Chemkleen 2010LP/181ALP bath (composed of
1.25 vol. % of Chemkleen 2010LP (a phosphate-free alkaline cleaner
available from PPG) and 0.125 vol. % of Chemkleen 181 ALP (a
phosphate-free blended surfactant additive, available from PPG) in
deionized water) in a stainless steel spray tank using vee-jet
nozzles at 10 to 15 psi, for two minutes at 120.degree. F. This was
followed by immersion rinse in DI water for 15 seconds, and final
spray rinse with DI water for 15 seconds.
[0254] Immediately after spray rinsing, the cleaned panels were
introduced into the conversion baths.
[0255] The first set of panels were pretreated with Zircobond 1.5,
a zirconium-conversion commercially available from PPG Industries,
Inc. A 5-gallon bath was prepared as per manufacturer's instruction
to yield a pH of 4.72, a zirconium concentration of 200 ppm, and a
free fluoride concentration of 101 ppm. The panels were pretreated
by immersion into the conversion bath at 80.degree. F. with low
agitation, for 2 minutes. The panels were spray rinsed with DI
water for 20 to 30 seconds, and air dried using a Hi-Velocity
handheld blow-dryer made by Oster.RTM. (model number
078302-300-000) on high-setting at a temperature of about
50-55.degree. C. until fully dry (about 3 to 5 minutes).
[0256] The second set of panels were pretreated with a lithium
hydroxide conversion composition. The lithium hydroxide conversion
composition was composed of 0.15 wt. % of lithium carbonate
(available from Acros Organics) in deionized water. The panels were
pretreated by immersion into a 3-gallon bath at ambient temperature
for 1 minute, without agitation. Immediately after conversion, the
panels were air dried using a Hi-Velocity handheld blow-dryer made
by Oster.RTM. (model number 078302-300-000) on high-setting at a
temperature of about 50-55.degree. C. until fully dry (about 3 to 5
minutes).
[0257] The third set of panels were pretreated with a lithium
carbonate conversion composition. The lithium carbonate conversion
composition was composed of 0.15 wt. % of lithium carbonate
(available from Acros Organics) in deionized water. The panels were
pretreated by immersion into a 3-gallon bath at ambient temperature
for 1 minute, without agitation. Immediately after conversion, the
panels were air dried using a Hi-Velocity handheld blow-dryer made
by Oster.RTM. (model number 078302-300-000) on high-setting at a
temperature of about 50-55.degree. C. until fully dry (about 3 to 5
minutes).
[0258] The pretreated panels were electrocoated with cationic
ED6280Z paint (available from PPG) using rectifier (Xantrex Model
XFR600-2). A coating dry film thickness of 0.8 mil was achieved by
passing a 24.5 C, 21.5 C, and 21.0 C charge for the zirconium,
lithium hydroxide, and lithium carbonate conversioned panels,
respectively, at a current limit of 0.5 A, and an applied
electrical potential of 220 V after a 30 second ramp time using a
direct current rectifier (Xantrex Model XFR600-2). The ED6280Z
paint bath was maintained at 90.degree. F., with a stir rate of 340
rpm. The electrocoated panels were spray rinsed with DI water. The
panels were baked in an electric oven (Despatch Model LFD-1-42) at
177.degree. C. for 25 minutes. The coating thickness was measured
using a Permascope (Fischer Technology Inc. Model FMP40C).
[0259] Two corrosion test methods were utilized to evaluate the
corrosion performance of the panels: ASTM G85 A2 Cyclic Acidified
Salt Fog Testing for 3 weeks, and a filiform corrosion testing for
6 weeks. For the latter test, the panels were placed horizontally
in a dessicator containing a thin layer of 12 N hydrochloric acid
(HCl) for 1 hr at ambient temperature, such that only the HCl fumes
shall come in contact with the sample. Within 5 mins, the panels
were placed in a vertical orientation in a humidity cabinet
maintained at 40.degree. C. and 80% relative humidity for 6 weeks.
Duplicate panels were included for each testing. Prior to corrosion
testing, the panels were scribed with an X-configuration. The
scribe was positioned with the top legs on the as-milled surface
and the bottom legs on the sanded surface. Each leg was 40 mm
long.
[0260] Corrosion damage was measured as the perpendicular distance
from the scribe to tip of the filament or blister. Each panel
provided two sets of five measurements: a set from the top legs for
the as-milled surface, and another set from the bottom legs for the
sanded surface. Measurements were taken from the five longest
corrosion sites. The average corrosion damage was calculated based
on a total often measurements from duplicate panels. All readings
were measured using a Fowler Sylvac digital caliper Model S
235.
[0261] The average corrosion damage is tabulated in Table 15.
Relative to the control Zirconium conversion, both lithium
hydroxide and lithium carbonate conversions displayed better
corrosion performance on sanded 6111 aluminum alloys. Lithium
hydroxide also exhibited superior corrosion performance on the
as-milled surface.
TABLE-US-00016 TABLE 15 Average corrosion damage (Example NN)
Average Corrosion Damage (mm) As-milled (unsanded) Sanded Test
Zirconium Lithium Lithium Zirconium Lithium Lithium Method
(control) Hydroxide Carbonate (control) Hydroxide Carbonate
Filiform 4.93 1.74 4.24 12.53 5.30 4.49 Corrosion Test ASTM 2.76
1.92 5.57 10.39 5.01 5.20 G85 A2
* * * * *