U.S. patent application number 14/855252 was filed with the patent office on 2016-01-07 for nickel-chromium nanolaminate coating having high hardness.
The applicant listed for this patent is Mdoumetal, Inc.. Invention is credited to Glenn Sklar.
Application Number | 20160002803 14/855252 |
Document ID | / |
Family ID | 51538035 |
Filed Date | 2016-01-07 |
United States Patent
Application |
20160002803 |
Kind Code |
A1 |
Sklar; Glenn |
January 7, 2016 |
Nickel-Chromium Nanolaminate Coating Having High Hardness
Abstract
The present disclosure describes electrodeposited nanolaminate
materials having layers comprised of nickel and/or chromium with
high hardness. The uniform appearance, chemical resistance, and
high hardness of the nanolaminate NiCr materials described herein
render them useful for a variety of purposes including wear
(abrasion) resistant barrier coatings for use both in decorative as
well as demanding physical, structural and chemical
environments.
Inventors: |
Sklar; Glenn; (Seattle,
WA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Mdoumetal, Inc. |
Seattle |
WA |
US |
|
|
Family ID: |
51538035 |
Appl. No.: |
14/855252 |
Filed: |
September 15, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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PCT/US14/30381 |
Mar 17, 2014 |
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14855252 |
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61802112 |
Mar 15, 2013 |
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Current U.S.
Class: |
428/621 ;
205/176; 205/76; 428/634; 428/635 |
Current CPC
Class: |
C25D 9/04 20130101; C25D
3/06 20130101; C25D 1/00 20130101; C25D 5/14 20130101; C25D 3/12
20130101; C25D 5/18 20130101; C25D 3/38 20130101; C25D 5/36
20130101; C25D 3/54 20130101; C25D 5/34 20130101; B32B 15/01
20130101; C25D 3/562 20130101; C25D 3/20 20130101 |
International
Class: |
C25D 3/56 20060101
C25D003/56; C25D 3/20 20060101 C25D003/20; B32B 15/01 20060101
B32B015/01; C25D 3/54 20060101 C25D003/54; C25D 9/04 20060101
C25D009/04; C25D 1/00 20060101 C25D001/00; C25D 3/12 20060101
C25D003/12; C25D 3/38 20060101 C25D003/38 |
Claims
1. A process for forming a multilayered nickel and chromium
containing coating on a surface of a substrate or mandrel by
electrodeposition comprising: (a) providing one or more electrolyte
solutions comprising a nickel salt and/or a chromium salt; (b)
providing a conductive substrate or mandrel for electrodeposition;
(c) contacting at least a portion of the surface of the substrate
or mandrel with one of said one or more electrolyte solutions; (d)
passing a first electric current through the substrate or mandrel,
to deposit a first layer comprising either nickel or an alloy
thereof, on the substrate or mandrel; and passing a second electric
current through the substrate, to deposit a second layer comprising
a nickel-chromium alloy on the surface; (e) repeating step (d) two
or more times thereby producing a multilayered coating having first
layers of nickel, or an alloy thereof, and second layers of a
nickel-chromium alloy on at least a portion of the surface of the
substrate or mandrel; and optionally separating the substrate or
mandrel from the coating.
2. The process of claim 1, wherein: said providing one or more
electrolyte solutions comprises providing an electrolyte solution
comprising a nickel salt and a chromium salt; passing an electric
current through said substrate or mandrel comprises alternately
pulsing said electric current for predetermined durations between
said first electrical current and said second electrical current;
where said first electrical current is effective to electrodeposit
a first composition comprising nickel or an alloy of nickel and
chromium; and where said second electrical current is effective to
electrodeposit a second composition comprising nickel and chromium;
thereby producing a multilayered alloy having alternating first and
second layers, said first layer comprising either nickel or an
alloy thereof, and said second layer comprising a nickel-chromium
alloy on at least a portion of the surface of the substrate or
mandrel.
3. The process of claim 1, wherein at least one of said one or more
electrolyte solutions is an aqueous solution comprising one or more
complexing agents.
4. The process of claim 3, wherein said complexing agent is
selected from one or more, two or more or three or more of citric
acid, EDTA, triethanolamine (TEA), ethylenediamine (En), formic
acid, acetic acid, hydroxyacetic acid, malonic acid, or an alkali
metal or ammonium salt of any thereof.
5. (canceled)
6. The process of claim 1, wherein the first electric current
ranges from approximately 10 mA/cm.sup.2 to approximately 100
mA/cm.sup.2, and wherein the second electric current ranges from
approximately 100 mA/cm.sup.2 to approximately 500 mA/cm.sup.2.
7-13. (canceled)
14. The process of claim 1, wherein said first layer comprises
greater than about 92% nickel by weight and a balance of other
elements.
15. The process of claim 1, wherein said second layer comprises
about 10% to about 21%, chromium by weight and a balance of other
elements.
16-17. (canceled)
18. The process of claim 1, wherein the first layer and/or the
second layer comprises one to four or more elements selected
independently for each layer from the group consisting of C, Co,
Cu, Fe, In, Mn, Nb, W, Mo, and P.
19. (canceled)
20. The process of claim 1, comprising fifty or more alternating
first layers and second layers.
21. An object or coating comprising a coating prepared by the
method of claim 1.
22. An object or coating comprising a multilayered coating
comprising a plurality of alternating first layers of nickel, or an
alloy comprising nickel, and second layers of an alloy comprising
nickel and chromium, and optionally comprising a substrate.
23-27. (canceled)
28. The object or coating of any of claim 22, wherein each first
layer comprises greater than about 92% nickel, and wherein each
second layer comprises chromium in a range independently selected
from 10%-21% chromium.
29-34. (canceled)
35. The object or coating of claim 22, wherein said first layers
consist of nickel or a nickel chromium alloy and said second layers
consist of a nickel-chromium alloy and wherein said coating has a
Vickers microhardness as measured by ASTM E384-11e1 of 550-750,
750-800, or 800-850 without heat treatment.
36. (canceled)
37. The object or coating of claim 22, wherein said substrate
comprises one or more elements selected from the group consisting
of C, Co, Cu, Fe, In, Mn, Nb, W, Mo, and P.
38-39. (canceled)
40. The object or coating of claim 22, wherein said object resists
corrosion of said substrate caused by exposure to one or more of
water, air, acid, base, salt water and/or H.sub.2S.
41. The object or coating of claim 37, wherein said first layers
consist of nickel, or a nickel chromium alloy, and said second
layers consist of a nickel-chromium alloy, and wherein said coating
has a Vickers microhardness as measured by ASTM E384-11e1 of
550-750, 750-800, or 800-850 without heat treatment.
42. (canceled)
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
application 61/802,112, filed Mar. 15, 2013, which application is
incorporated herein by reference in its entirety.
BACKGROUND
[0002] Electrodeposition is recognized as a low-cost method for
forming a dense coating on a variety of conductive materials,
including metals, alloys, conductive polymers and the like.
Electrodeposition has also been successfully used to deposit
nanolaminated coatings on non-conductive material such as
non-conductive polymers by incorporating sufficient materials into
the non-conductive polymer to render it sufficiently conductive or
by treating the surface to render it conductive, for example by
electroless deposition of nickel, copper, silver, cadmium etc. a
variety of engineering applications.
[0003] Electrodeposition has also been demonstrated as a viable
means for producing laminated and nanolaminated coatings, materials
and objects, in which the individual laminate layers may vary in
the composition of the metal, ceramic, organic-metal composition,
and/or microstructure features. Laminated coatings and materials,
and in particular nanolaminated metals, are of interest for a
variety of purposes, including structural, thermal, and corrosion
resistance applications because of their unique toughness, fatigue
resistance, thermal stability, wear (abrasion resistance and
chemical properties.
SUMMARY
[0004] The present disclosure is directed to the production NiCr
nanolaminated materials having a high hardness. The materials have
a variety of uses including, but not limited to, the preparation of
coatings that protect an underlying substrate, and which may also
increase its strength. In one embodiment hard NiCr coatings and
materials are wear/abrasion resistant and find use as wear
resistant coatings in tribological applications. In another
embodiment the hard NiCr coatings prevent damage to the underlying
substrates. Where the NiCr materials are applied as a coating that
is more noble then the underlying material upon which it is placed,
it may function as a corrosion resistant barrier coating.
DESCRIPTION
1.1 Overview
[0005] The present disclosure is directed to the method of
producing laminate materials and coatings comprising layers each
comprising nickel or nickel and chromium. The materials, which are
prepared by electrodeposition, have a Vickers hardness value up to
about 750 without the addition of other elements or heat
treatments.
[0006] In one embodiment the disclosure is directed to an
electrodeposition processes for forming a multilayered nickel and
chromium containing coating on a substrate or mandrel comprising:
[0007] (a) providing one or more electrolyte solutions comprising a
nickel salt and/or a chromium salt; [0008] (b) providing a
conductive substrate or mandrel for electrodeposition; [0009] (c)
contacting at least a portion of the substrate or mandrel with one
of said one or more electrolyte solutions; and [0010] (d) passing a
first electric current through the substrate or mandrel, to deposit
a first layer comprising either nickel or an alloy thereof on the
surface; and passing a second electric current through the
substrate, to deposit second layer comprising a nickel-chromium
alloy on the surface; [0011] (e) repeating step (d) two or more
times thereby producing a multilayered coating having first layers
of nickel or an alloy thereof and second layers of a
nickel-chromium alloy on at least a portion of the surface of the
substrate or mandrel.
[0012] The method may further comprise the step of separating said
substrate or mandrel from the coating, where the coating forms an
object comprised of the laminate material.
[0013] The high hardness coating produced by the process typically
has alternating first and second layers. The first layers are each
from about 25 nm to about 75 nm thick, and comprises from about 92%
to about 99% nickel, with the balance typically comprising
chromium. The second layers are each from about 125 nm to about 175
nm thick, and typically comprise from about 10% to about 21%
chromium by weight with the balance typically comprising
nickel.
1.2 Definitions
[0014] "Laminate" or "laminated" as used herein refers to materials
that comprise a series of layers, including nanolaminated
materials.
[0015] "Nanolaminate" or "nanolaminated" as used herein refers to
materials that comprise a series of layers less than 1 micron.
[0016] All compositions given as percentages are given as percent
by weight unless stated otherwise.
1.3 Nanolaminate NiCr Coatings
1.3.1 Nanolaminate NiCr Materials and Coatings and Methods of Their
Preparing
[0017] Electrodeposition has been demonstrated as a viable means
for producing nanolaminated metal materials and coatings in which
the individual laminate layers may vary in the composition or
structure of the metal components. In addition, electrodeposition
permits the inclusion of other components, such as ceramic
particles and organic-metal components.
[0018] Multi-laminate materials having layers with different
compositions can be realized by moving a mandrel or substrate from
one bath to another and electrodepositing a layer of the final
material. Each bath represents a different combination of
parameters, which may be held constant or varied in a systematic
manner. Accordingly, laminated materials may be prepared by
alternately electroplating a substrate or mandrel in two or more
electrolyte baths of differing electrolyte composition and/or under
differing plating conditions (e.g., current density and mass
transfer control). Alternatively, laminated materials may be
prepared using a single electrolyte bath by varying the
electrodeposition parameters such as the voltage applied, the
current density, mixing rate, substrate or mandrel movement (e.g.,
rotation) rate, and/or temperature. By varying those and/or other
parameters, laminated materials having layers with differing metal
content can be produced in a single bath.
[0019] The present disclosure provides a process for forming a
multilayered nickel and chromium containing coating on a substrate
or mandrel by electrodeposition comprising: [0020] (a) providing
one or more electrolyte solutions (baths) comprising a nickel salt
and/or a chromium salt; [0021] (b) providing a conductive substrate
or mandrel suitable for electrodeposition; [0022] (c) contacting at
least a portion of the substrate or mandrel with one of said one or
more electrolyte solutions; [0023] (d) passing a first electric
current through the substrate or mandrel, to deposit a first layer
comprising either nickel or an alloy thereof on the substrate or
mandrel; and passing a second electric current through the
substrate, to deposit second layer comprising a nickel-chromium
alloy on the surface; and [0024] (e) repeating step (d) two or more
times thereby producing a multilayered coating having first layers
of nickel or an alloy thereof and second layers of a
nickel-chromium alloy on at least a portion of the surface of the
substrate or mandrel.
[0025] Where separate baths are employed to deposit the first and
second layers step (d) includes contacting at least a portion of
the substrate or mandrel that having the first layer deposited on
it with a second of said one or more electrolyte solutions (baths)
prior to passing a second electric current through the substrate,
to deposit second layer comprising a nickel-chromium alloy on the
surface.
[0026] Where the electroplated material is desired as an object
that is "electroformed" or as a material separated from the
substrate or mandrel, the method may further comprise a step of
separating the substrate or mandrel from the electroplated coating.
Where a step of separating the electroplated material form the
substrate or mandrel is to be employed, the use of electrodes
(mandrel) that do not form tight bonds with the coating are
desirable, such as titanium electrode (mandrel).
[0027] In one embodiment, where a single bath is used to deposit
the first and second layers, providing one or more electrolyte
solutions comprises providing a single electrolyte solution
comprising a nickel salt and a chromium salt, and passing an
electric current through said substrate or mandrel comprises
alternately pulsing said electric current for predetermined
durations between said first electrical current density and said
second electrical current density; where the first electrical
current density is effective to electrodeposit a first composition
comprising either nickel or an alloy of nickel and chromium; and
the second electrical current density is effective to
electrodeposit a second composition comprising nickel and chromium;
the process is repeated to producing a multilayered alloy having
alternating first and second layers on at least a portion of said
surface of the substrate or mandrel.
[0028] Regardless of whether the laminated material is produced by
electroplating in more than one bath (e.g., alternately plating in
two different baths) or in a single baths, the electrolytes
employed may be aqueous or non-aqueous. Where aqueous baths are
employed they may benefit from the addition of one or more, two or
more, or three or more complexing agents, which can be particularly
useful in complexing chromium in the +3 valency. Among the
complexing agents that may be employed in aqueous baths are one or
more of citric acid, ethylendiaminetetraacetic acid (EDTA),
triethanolamine (TEA), ethylenediamine (En), formic acid, acetic
acid, hydroxyacetic acid, malonic acid, or an alkali metal salt or
ammonium salt of any thereof. In one embodiment the electrolyte
used in plating comprises a Cr.sup.+3 salt (e.g., a tri-chrome
plating bath). In another embodiment the electrolyte used in
plating comprises either Cr.sup.+3 and one or more complexing
agents selected from citric acid, formic acid, acetic acid,
hydroxyacetic acid, malonic acid, or an alkali metal salt or
ammonium salt of any thereof. In still another embodiment the
electrolyte used in plating comprises either Cr.sup.+3 and one or
more amine containing complexing agents selected from EDTA,
triethanolamine (TEA), ethylenediamine (En), or salt of any
thereof.
[0029] The temperature at which the electrodeposition process is
conducted may alter the composition of the electrodeposit. Where
the electrolyte(s) employed are aqueous, the electrodeposition
process will typically be kept in the range of about 18.degree. C.
to about 45.degree. C. (e.g., 18.degree. C. to about 35.degree.
C.). for the deposition of both the first and second layers. Both
potentiostatic and galvanostatic control of the electrodeposition
of the first and second layers is possible regardless of whether
those layers are applied from different electrolyte baths or from a
single bath. In one embodiment, a single electrolyte bath is
employed and the first electrical current ranges from approximately
10 mA/cm.sup.2 to approximately 100 mA/cm.sup.2 for the deposition
of the first layers. In that embodiment the second electrical
current ranges from approximately 100 mA/cm.sup.2 to approximately
500 mA/cm.sup.2 for the deposition of the second layers.
[0030] Plating of each layer may be conducted either continuously
or by pulse or pulse reverse plating. In one embodiment, the first
electrical current is applied to the substrate or mandrel in pulses
ranging from approximately 0.001 second to approximately 1 seconds.
In another embodiment, the second electrical current is applied to
the substrate or mandrel in pulses ranging from approximately 1
second to approximately 100 seconds. In another embodiment, wherein
alternating Ni and Cr containing layer are electrodeposited, the
electrodeposition may employ periods of DC plating followed by
periods of pulse plating.
[0031] In one embodiment, plating of the nearly pure nickel layer
may be conducted either by direct current or by pulse plating. In
one such embodiment, the first electrical current is applied to the
substrate or mandrel in pulses ranging from approximately 0.001
second to approximately 1 seconds. In another embodiment, the
second electrical current is applied to the substrate or mandrel in
pulses ranging from approximately 1 second to approximately 100
seconds. In another embodiment, wherein alternating Ni and Cr
containing layer are electrodeposited, the electrodeposition may
employ periods of DC plating followed by periods of pulse
plating.
[0032] To ensure adequate binding of NiCr coatings to substrates it
is necessary to preparing the substrate for the electrodeposition
(e.g., the surface must be clean, electrochemically active, and the
roughness determined to be in in an adequate range). In addition,
depending on the substrate it may be desirable to employ a strike
layer, particularly where the substrate is a polymer or plastic
that has previously been rendered conductive by electroless plating
or by chemical conversion of its surface, as in the case for
zincate processing of aluminum, which is performed prior to the
electroless or electrified deposition. Where a strike layer is
applied, it may be chosen from an of a number of metals including,
but not limited to, copper nickel, zinc, cadmium, platinum etc. In
one embodiment, the strike layer is nickel or a nickel alloy from
about 100 nm to about 1000 nm or about 250 nm to about 2500 nm
thick. In another embodiment, a first layer applied to a substrate
may act as a strike layer, in which case it is applied so that it
is directly in contact with a substrate, or in the case of a
polymeric substrate rendered conductive by electroless deposition
of a metal, directly in contact with the electroless metal layer.
Accordingly, in one embodiment a first layer is in contact with the
substrate or mandrel. In another embodiment, the second layer is in
contact with the substrate or mandrel.
[0033] The hard nanolaminate materials, such as coatings, produced
by the processes described above will typically comprise
alternating first and second layers in addition to any strike layer
applied to the substrate. The first layers each having a thickness
independently selected from about 25 nm to about 75 nm, from about
25 nm to about 50 nm, from about 35 nm to about 65 nm, from about
40 nm to about 60 nm, or from about 50 nm to about 75 nm. The
second layers having thickness independently from about 125 nm to
about 175 nm, from about 125 nm to about 150 nm, from about 135 nm
to about 165 nm, from about 140 nm to about 160 nm, or from about
150 nm to about 175 nm.
[0034] First layers may typically comprise greater than about 92%,
93%, 94%, 95%, 96%, 97%, 98% or 99% nickel. The balance of first
layers may be chromium, or may be comprised of one or more, two or
more, three or more, or four or more elements selected
independently for each first layer from C, Co, Cr, Cu, Fe, In, Mn,
Nb, Sn, W, Mo, and P. In one embodiment the balance of the first
layers are each an alloy comprising chromium and one or more
elements selected independently for each layer from C, Co, Cu, Fe,
Ni, W, Mo and/or P.
[0035] Second layers may typically comprise about 5% to about 40%,
about 5% to about 21%, about 10% to about 14%, about 12% to about
16%, about 14% to about 18%, about 16 to about 21%, about 18% to
about 21% or about 18% to about 40% chromium. The balance of second
layers may be nickel, or may be comprised of nickel and one or
more, two or more, three or more, or four or more elements selected
independently for each second layer from C, Co, Cu, Fe, In, Mn, Mo,
P, Nb, Ni and W. In one embodiment the balance of the second layers
is an alloy comprising nickel and one or more elements selected
independently for each layer from C, Co, Cr, Cu, Mo, P, Fe, Ti and
W.
[0036] In one embodiment, for an element to be considered as being
present, it is contained in the electrodeposited material in
non-trivial amounts. In such an embodiment a trivial amount may be
less than about 0.005%, 0.01%, 0.05% or 0.1% by weight.
Accordingly, non-trivial amounts may be greater than 0.005%, 0.01%,
0.05% or 0.1% by weight. Laminated or nanolaminated materials
including coatings prepared as described herein comprise two or
more, three or more, four or more, six or more, eight or more, ten
or more, twenty or more, forty or more, fifty or more, 100 or more,
200 or more, 500 or more or 1000 or more alternating first and
second layers. In such embodiments, the first and second layers are
counted as pairs of first and second layers. Accordingly, two
layers each having a first layer and second layer, consists of a
total of four laminate layers (i.e., each layer is counted
separately).
[0037] In addition to the methods of preparing hard NiCr materials,
the present disclosure is directed to hard NiCr materials,
including hard NiCr coatings and electroformed NiCr objects
prepared by the methods described above.
1.3.2 Properties and Applications of Nanolaminate NiCr Coatings
1.3.2.1 Surface Properties
[0038] The hard NiCr materials described herein have a number of
properties that render them useful for both industrial and
decorative purposes. The coatings applied are self-leveling and
depending on the exact composition of the outermost layer can be
reflective to visible light. Accordingly, the hard NiCr materials
may serve as a replacement for chrome finishes in a variety of
application where reflective metal surfaces are desired. Such
applications include, but are not limited to, minors, automotive
details such as bumpers or fenders, decorative finishes and the
like.
[0039] In one embodiment the laminated NiCr coatings described
herein have a surface roughness (arithmetical mean roughness or Ra)
of less than 0.1 micrometer (e.g., 0.09, 0.08, 0.07, or 0.05
microns).
1.3.2.2 Hardness
[0040] Through the use of nanolamination it is possible to increase
the hardness of NiCr alloys above the hardness observed for
homogeneous electrodeposited NiCr compositions (alloys) that have
not been heat treated and have the same thickness and average
composition as the hard NiCr nanolaminate material. Then laminated
NiCr materials have a Vickers microhardness as measured by ASTM
E384-11e1of 550-750, 550-600, 600-650, 650-700, 700-750 or greater
than 750 but less than about 900, 950, 1000 or 1100 units without
heat treatment. The use of heat treatments in the presence of other
elements such as P, C in the first and second layers can increase
the hardness of the coating.
[0041] In another embodiment the NiCr materials described herein
comprising alternating first and second layers, where the first
layers that comprise nickel or comprise a nickel-chromium alloy,
and the second layers comprise a nickel-chromium alloy. Such
materials have a Vickers microhardness as measured by ASTM
E384-11e1 of 550-750, 550-600, 600-650, 650-700, 700-750, 750-800,
or 800-850 without heat treatment.
[0042] In one embodiment, the NiCr materials described herein
consist of alternating first and second layers, where the first
layers consist of a nickel or a nickel-chromium alloy and second
layers consist of a nickel-chromium alloy. Such materials have a
Vickers microhardness as measured by ASTM E384-11e1 of 550-750,
550-600, 600-650, 650-700, 700-750, 750-800 or 800-850 without heat
treatment.
1.3.2.3 Abrasion Resistance
[0043] Due to their high hardness the laminated NiCr materials are
useful as a means of providing resistance to abrasion, especially
when they are employed as coatings. In one embodiment, the
nanolaminate NiCr coatings that have not been heat treated display
5%, 10%, 20%, 30% or 40% less loss of weight than homogeneous
electrodeposited NiCr compositions (alloys) that have not been heat
treated and have the same thickness and average composition as the
hard NiCr nanolaminate material when subject to testing on a Taber
Abraser equipped with CS-10 wheels and a 250 g load and operated at
room temperature at the same speed for both samples (e.g., 95 RPM).
In another embodiment, the laminated NiCr compositions display a
higher abrasion resistance when subject to testing under ASTM D4060
than their homogeneous counterpart (e.g., homogeneous
electrodeposited counterpart having the average composition of the
laminated NiCr composition).
1.3.2.4 Corrosion Protection
[0044] The behavior of organic, ceramic, metal and metal-containing
coatings in corrosive environments depends primarily on their
chemistry, microstructure, adhesion, their thickness and galvanic
interaction with the substrate to which they are applied.
[0045] NiCr generally acts as barrier coating being more
electronegative (more noble) than substrates to which it will be
applied, such as iron-based substrates. As such, NiCr coatings act
by forming a barrier to oxygen and other agents (e.g., water, acid,
base, salts, and/or H.sub.2S) causing corrosive damage, including
oxidative corrosion. When a barrier coating that is more noble than
its underlying substrate is maned or scratched, or if coverage is
not complete, the coatings will not work and may accelerate the
progress of substrate corrosion at the substrate-coating interface,
resulting in preferential attack of the substrate. Consequently,
coatings prepared from the hard NiCr coatings described herein
offer advantages over softer NiCr nanolaminate coatings as they are
less likely to permit a scratch to reach the surface of a corrosion
susceptible substrate. Another advantage offered by the hard NiCr
laminate coatings described herein are their fully dense structure,
which lacks any significant pores or micro-cracks that extend from
the surface of the coating to the substrate. To avoid the formation
of microcracks the first layer can be a nickel rich ductile layer
that hinders the formation of continuous cracks from the coating
surface to the substrate. To the extent that microcracks occur in
the high chromium layers, they are small and tightly spaced. The
lack of pores and continuous microcracks more effectively prohibits
corrosive agents from reaching the underling substrate and renders
the laminate NiCr coatings described herein more effective as a
barrier coating to oxidative damage of a substrate than an
equivalent thickness of electrodeposited chromium.
2.0 Certain Embodiments
[0046] 1. A process for forming a multilayered nickel and chromium
containing coating on a surface of a substrate or mandrel by
electrodeposition comprising: [0047] (a) providing one or more
electrolyte solutions comprising a nickel salt and/or a chromium
salt; [0048] (b) providing a conductive substrate or mandrel for
electrodeposition; [0049] (c) contacting at least a portion of the
surface of the substrate or mandrel with one of said one or more
electrolyte solutions; [0050] (d) passing a first electric current
through the substrate or mandrel, to deposit a first layer
comprising either nickel, or an alloy thereof, on the substrate or
mandrel; and passing a second electric current through the
substrate, to deposit a second layer comprising a nickel-chromium
alloy on the surface; [0051] (e) repeating step (d) two or more
times thereby producing a multilayered coating having first layers
of nickel, or an alloy thereof, and second layers of a
nickel-chromium alloy on at least a portion of the surface of the
substrate or mandrel; and optionally separating the substrate or
mandrel from the coating. [0052] 2. The process of embodiment 1,
wherein: [0053] said providing one or more electrolyte solutions
comprise providing an electrolyte solution comprising a nickel salt
and a chromium salt; [0054] passing an electric current through
said substrate or mandrel comprises alternately pulsing said
electric current for predetermined durations between said first
electrical current and said second electrical current (e.g.,
pulsing for predetermined durations at a first electrical current
value and then at a second electrical current value); [0055] where
said first electrical current is effective to electrodeposit a
first composition comprising nickel or an alloy of nickel and
chromium; and [0056] where said second electrical current is
effective to electrodeposit a second composition comprising nickel
and chromium; [0057] thereby producing a multilayered alloy having
alternating first and second layers, said first layer comprising
either nickel, or an alloy thereof, and said second layer
comprising a nickel-chromium alloy on at least a portion of the
surface of the substrate or mandrel. [0058] 3. The process of
embodiment 1 or embodiment 2, wherein at least one of said one or
more electrolyte solutions is an aqueous bath (e.g., aqueous
solution) comprising one or more complexing agents. [0059] 4. The
process of embodiment 3, wherein said complexing agent is selected
from one or more, two or more, or three or more of citric acid,
ethylenediaminetetraacetic acid (EDTA), triethanolamine (TEA),
ethylenediamine (En), formic acid, acetic acid, hydroxyacetic acid,
malonic acid or an alkali metal or ammonium salt of any thereof.
[0060] 5. The process of any of embodiments 1-4, wherein said
passing said first electric current through said substrate or
mandrel and passing said second electric current through said
substrate or mandrel are conducted at a temperature ranging from
approximately (about) 18.degree. C. to approximately (about)
35.degree. C., or from approximately (about) 18.degree. C. to
approximately (about) 45.degree. C. [0061] 6. The process of any of
embodiments 1-5, wherein the first electric current has a range
from approximately (about) 10 mA/cm.sup.2 to approximately (about)
100 mA/cm.sup.2 [0062] 7. The process of any of embodiments 1-6,
wherein the second electric current has a range from approximately
(about) 100 mA/cm.sup.2 to approximately (about) 500 mA/cm.sup.2.
[0063] 8. The process of any of embodiments 1-7, wherein the first
electrical current is applied to the substrate or mandrel in pulses
ranging from approximately (about) 0.001 second to approximately
(about) 1.00 seconds. [0064] 9. The process of any of embodiments
1-8, wherein the second electrical current is applied to the
substrate or mandrel in pulses ranging from approximately (about)
0.001 second to approximately (about) 1.00 seconds. [0065] 10. The
process of any of embodiments 1-9, wherein said first layer is in
contact with said substrate or mandrel. [0066] 11. The process of
any of embodiments 1-9, wherein said second layer is in contact
with said substrate or mandrel. [0067] 12. The process of any of
embodiments 1-11, wherein said first layer has a thickness from
about 25 nm to about 75 nm, from about 25 nm to about 50 nm, from
about 35 nm to about 65 nm, from about 40 nm to about 60 nm, or
from about 50 nm to about 75 nm. [0068] 13. The process of any of
embodiments 1-12, wherein said second layer has a thickness from
about 125 nm to about 175 nm, from about 125 nm to about 150 nm,
from about 135 nm to about 165 nm, from about 140 nm to about 160
nm, or from about 150 nm to about 175 nm. [0069] 14. The process of
any of embodiments 1-13, wherein said first layer comprises greater
than about 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% nickel by
weight and a balance of other elements. [0070] 15. The process of
any of embodiments 1-14, wherein said second layer comprises about
10% to about 21%, about 10% to about 14%, about 12% to about 16%,
about 14% to about 18%, about 16% to about 21%, about 18% to about
21% or about 18% to about 40% chromium by weight and a balance of
other elements. [0071] 16. The process of embodiment 14, wherein
said first layer comprises greater than about 92%, 93%, 94%, 95%,
96%, 97%, 98% or 99% nickel, and the balance of the first layer is
chromium. [0072] 17. The process of embodiment 15, wherein said
second layer comprises about 10% to about 21%, about 10% to about
14%, about 12% to about 16%, about 14% to about 18%, about 16% to
about 21%, about 18% to about 21% or about 18% to about 40%
chromium, and the balance of the second layer is nickel. [0073] 18.
The process of any of embodiments 1-15, wherein the first layer
and/or the second layer comprises one or more, two or more, three
or more or four or more elements selected independently for each
layer from the group consisting of C, Co, Cu, Fe, In, Mn, Nb, W,
Mo, and P. [0074] 19. The process of embodiment 18, wherein said
elements selected independently for each layer are each present in
a non-trivial amount greater than 0.005%, 0.01%, 0.05% or 0.1% by
weight. [0075] 20. The process of any of embodiments 1-19,
comprising two or more, three or more, four or more, six or more,
eight or more, ten or more, twenty or more, forty or more, fifty or
more, 100 or more, 200 or more, 500 or more or 1000 or more
alternating first layers and second layers. [0076] 21. An object or
coating comprising a multilayered nickel and chromium containing
coating prepared by the method of any of embodiments 1-20. [0077]
22. An object or coating comprising a multilayered coating
comprising a plurality of alternating first layers of nickel or an
alloy comprising nickel, and second layers of an alloy comprising
nickel and chromium, and optionally comprising a substrate. [0078]
23. The object or coating of embodiment 22, wherein said multilayer
coating comprises two or more, three or more, four or more, six or
more, eight or more, ten or more, twenty or more, forty or more,
fifty or more, 100 or more, 200 or more, 500 or more or 1000 or
more alternating first and second layers. [0079] 24. The object or
coating of any of embodiments 22-23, wherein said first layers have
a thickness from about 25 nm to about 75 nm, from about 25 nm to
about 50 nm, from about 35 nm to about 65 nm, from about 40 nm to
about 60 nm or from about 50 nm to about 75 nm. [0080] 25. The
object or coating of any of embodiments 22-24, wherein said second
layers have a thickness from about 125 nm to about 175 nm, from
about 125 nm to about 150 nm, from about 135 nm to about 165 nm,
from about 140 nm to about 160 nm or from about 150 nm to about 175
nm. [0081] 26. The object or coating of any of embodiments 22-25,
wherein said first layer is in contact with said substrate or
mandrel. [0082] 27. The object or coating of any of embodiments
22-26, wherein said second layer is in contact with said substrate
or mandrel. [0083] 28. The object or coating of any of embodiments
22-27, wherein said first layer comprises greater than about 92%,
93%, 94%, 95%, 96%, 97%, 98% or 99% nickel. [0084] 29. The object
or coating of any of embodiments 22-28, wherein each second layer
comprises chromium in a range independently selected from about 10%
to about 21%, about 10% to about 14%, about 12% to about 16%, about
14% to about 18%, about 16% to about 21%, about 18% to about 21% or
18%-40% chromium. [0085] 30. The object or coating of embodiment
28, wherein said first layer comprises greater than about 92%, 93%,
94%, 95%, 96%, 97%, 98% or 99% nickel and the balance of the first
layer is chromium. [0086] 31. The object or coating of embodiment
29, wherein said second layer comprises greater than about 10% to
about 21%, about 10% to about 14%, about 12% to about 16%, about
14% to about 18%, about 16% to about 21%, about 18% to about 21% or
about 18% to about 40% chromium and the balance of the second layer
is nickel. [0087] 32. The object or coating of any of embodiments
22-31, wherein said first and/or second layer comprises one or
more, two or more, three or more, or four or more elements selected
independently from the group consisting of C, Co, Cu, Fe, In, Mn,
Nb W, Mo, and P. [0088] 33. The object or coating of any of
embodiments 22-31, wherein each of said elements are present at
concentrations of 0.01% or greater. [0089] 34. The object or
coating of any of embodiments 22-33, comprising two or more, three
or more, four or more, six or more, eight or more, ten or more,
twenty or more, forty or more, fifty or more, 100 or more, 200 or
more, 500 or more or 1000 or more alternating first and second
layers. [0090] 35. The object or coating of any of embodiments
22-34, wherein said first layers consist of nickel or a nickel
chromium alloy and said second layers consist of a nickel-chromium
alloy and wherein said coating has a Vickers microhardness as
measured by ASTM E384-11e1 of about 550 to about 750, about 550 to
about 600, about 600 to about 650, about 650 to about 700, about
700 to about 750, about 750 to about 800 or about 800 to about 850
without heat treatment. [0091] 36. The object or coating of any of
embodiments 22-34, wherein said substrate comprises one or metals.
[0092] 37. The object or coating of embodiment 36, wherein said
substrate comprises one or more metals or other elements selected
from the group consisting of C, Co, Cu, Fe, In, Mn, Nb, W, Mo, and
P. [0093] 38. The object or coating of embodiment 37, wherein said
substrate is selected from iron or steel. [0094] 39. The object or
coating of any of embodiments 22-38, wherein said coating has fewer
cracks, pores, or microcracks than a monolithic coating of chromium
of substantially the same thickness (e.g., an electrodeposited
coating of chromium of substantially the same thickness deposited
under conditions suitable for deposition of second layers but
consisting of chromium). [0095] 40. The object or coating of any of
embodiments 22-39, wherein said object resists corrosion of said
substrate caused by exposure to one or more of water, air, acid,
base, salt water, and/or H2S. [0096] 41. The object or coating of
any of embodiments 36-40, wherein said first layers consists of
nickel, or a nickel chromium alloy, and second layers consist of a
nickel-chromium alloy, and wherein said coating has a Vickers
microhardness as measured by ASTM E384-11e1 of about 550 to about
750, about 550 to about 600, about 600 to about 650, about 650 to
about 700, about 700 to about 750, about 750 to about 800 or about
800 to about 850 without heat treatment. [0097] 42. The process of
any of embodiments 1-20, further comprising separating said
multilayered coating from said substrate or mandrel to form a
multilayered object.
* * * * *