U.S. patent application number 16/623019 was filed with the patent office on 2021-05-20 for zinc wrought alloy with improved coatability.
The applicant listed for this patent is Grillo-Werke AG. Invention is credited to Kathrin HESNAOUI, Armin MELZER, Frank PRENGER, Didier ROLLEZ, Markus VAN WESEL, Joanna VON KRIES, Jurgen WISNIEWSKI.
Application Number | 20210147962 16/623019 |
Document ID | / |
Family ID | 1000005400244 |
Filed Date | 2021-05-20 |
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United States Patent
Application |
20210147962 |
Kind Code |
A1 |
MELZER; Armin ; et
al. |
May 20, 2021 |
ZINC WROUGHT ALLOY WITH IMPROVED COATABILITY
Abstract
The present invention relates to a zinc wrought alloy with
improved coating properties as compared to known wrought alloys,
and to the use thereof for preparing semifinished products,
forgings, turned parts, locks, screw connections, locking
cylinders, sleeves, fittings, pressed parts, pneumatic parts,
hydraulic parts, mountings, valves and ball valves.
Inventors: |
MELZER; Armin; (Duisburg,
DE) ; PRENGER; Frank; (Duisburg, DE) ; ROLLEZ;
Didier; (Duisburg, DE) ; VAN WESEL; Markus;
(Duisburg, DE) ; VON KRIES; Joanna; (Hittbergen,
DE) ; WISNIEWSKI; Jurgen; (Duisburg, DE) ;
HESNAOUI; Kathrin; (Duisburg, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Grillo-Werke AG |
Duisburg |
|
DE |
|
|
Family ID: |
1000005400244 |
Appl. No.: |
16/623019 |
Filed: |
July 2, 2018 |
PCT Filed: |
July 2, 2018 |
PCT NO: |
PCT/EP2018/067824 |
371 Date: |
December 16, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C22C 18/04 20130101 |
International
Class: |
C22C 18/04 20060101
C22C018/04 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 4, 2017 |
EP |
17179645.1 |
Claims
1. A method of making an article, the method comprising including
in the article a zinc wrought alloy having an Al content of from 5%
by weight to 12% by weight, a Cu content of from 0.1% by weight to
4% by weight, an Mg content of from 0.001% by weight to 0.05% by
weight, wherein Zn is the balance to 100%, the article being one or
more of preparing forgings, turned parts, locks, screw connections,
locking cylinders, sleeves, fittings, pressed parts, pneumatic
parts, hydraulic parts, mountings, valves and/or ball valves.
2. The method according to claim 1, characterized in that lead is
not included in the alloy.
3. The method according to claim 1, characterized in that the
content of Al is from 5% to 12% by weight.
4. The method according to claim 1, characterized in that the
content of copper in the alloy is from 0.1% to 2.5% by weight.
5. The method according to claim 1, characterized in that the
content of magnesium in the alloy is from 0.003% by weight to 0.05%
by weight.
6. The method according to claim 1, characterized in that the alloy
further contains silicon.
7. The method according to claim 1, wherein said alloy has the
following composition: Al content of from 5% to 8% by weight, Cu
content of from 0.5% to 1.5% by weight, Mg content of from 0.003%
to 0.05% by weight, with zinc as the balance to reach 100% by
weight.
8. The method according to claim 1, wherein said alloy has the
following composition: Al content of from 9% to 12% by weight, a Cu
content of from 0.5% to 1.5% by weight, an Mg content of from
0.003% to 0.05% by weight, with zinc as the balance to reach 100%
by weight.
9. The method according to claim 1, wherein said alloy has a Ti
content of up to 1% by weight.
10. A manufactured object that comprises a zinc wrought alloy as
described in claim 1, the object being a semifinished product or an
article, wherein the object passes a salt spray test according to
DIN EN ISO 9227:2012, wherein the test requirements are considered
to be met if no corrosion in the form of white rust occurs on the
surface after 96 hours.
11. A manufactured object that comprises a Use of a zinc wrought
alloy as described in claim 1, the object being a semifinished
product or article, wherein the articles pass a condensation water
test according to DIN EN ISO 6270-2:2016, wherein the test
requirements are considered to be met if no blistering or corrosion
occurs on a surface of the object after 96 hours in a condensation
water chamber.
Description
[0001] The present invention relates to a zinc wrought alloy with
improved coating properties as compared to known wrought alloys,
and to the use thereof for preparing semifinished products,
forgings, turned parts, locks, screw connections, locking
cylinders, sleeves, fittings, pressed parts, pneumatic parts,
hydraulic parts, mountings, valves and ball valves.
[0002] A wide variety of zinc alloys are known in the prior
art.
[0003] As an example, EP 2675971 A--"Accessory consisting of a lock
accessory" may be mentioned. It discloses a zinc alloy with an Al
content of from 13 to 25%, a Cu content of from 0.2 to 3.5%, and an
Mg content of less than 0.1%, which is employed for lock
accessories.
[0004] EP 2 385 148 A--"Zinc alloy with high creep resistance"
relates to a zinc-aluminum alloy with an Al content of 10 to
<25%, a Cu content of 0.05 to 3%, an Mg content of from 0.001 to
0.1%, an Mn content of 0.05% to 1.0% and an Si content of from 0.05
to 1%. The disclosed alloy has a high creeping resistance and is
suitable for the furnace brazing and normal brazing of heat
exchangers.
[0005] U.S. Pat. No. 3,734,785--"Zinc forging alloy" claims a
zinc-based alloy with an Al content of 9 to 22%, a Cu content of
0.5 to 1.5%, and an Mg content of 0.01 to 0.03%, which is
particularly suitable for hot formability.
[0006] U.S. Pat. No. 3,880,679--"Method of forming zinc-aluminum
alloys with good machinability" describes zinc-aluminum alloys with
an Al content of 22 to 27%, a Cu content of 0 to 10%, an Mg content
of 0.01 to 1%, and a Bi content of 0.01 to 3%.
[0007] EP 0 679 198 A--"Method for producing Zn--Al--Cu alloy
articles by centrifugal or die casting" describes a zinc alloy with
an Al content of 6.0 to 8.0%, a Cu content of 3.2 to 4.3%, for
preparing articles by centrifugal casting in a rubber mold, or
pressure die-casting in a metal mold.
[0008] Further known are also zinc pressure die-casting alloys,
also referred to as ZAMAK.RTM.. These consist of
zinc-aluminum-copper-magnesium alloys, which cannot have the
corresponding strength properties, however.
[0009] In addition to processability in terms of production,
shaping or reshaping, the coatability of zinc alloys is also
relevant. Semifinished products, forgings, turned parts, locks,
screw connections, locking cylinders, sleeves, fittings, pressed
parts, pneumatic parts, hydraulic parts, mountings, valves and ball
valves consisting of corresponding alloys are often provided with
different coatings for improving the appearance and/or for
improving the corrosion resistance. In particular, a
copper-copper-nickel coating serves for both corrosion resistance
and appearance. Further, the coating with zinc and passivation
mainly serves for a very high corrosion resistance, being an
inexpensive alternative for a copper-copper-nickel coating.
[0010] The prior art with previous zinc wrought alloys is
problematic, especially in view of surface coating. It has been the
object of the present invention to provide a zinc-based wrought
alloy having improved coating properties as compared to the prior
art. This is to be achieved without including lead in the alloy. In
addition, the coating should have good corrosion properties, i.e.,
have as little tendency to corrosion as possible. Surprisingly, it
has been found that this is enabled by a low aluminum content of at
most 12% by weight in zinc wrought alloys.
[0011] "Alloying" basically means the preparation of an alloy by
melting a metal together with at least one other metal or
non-metal. If in the present application it is referred to the fact
that a metal or non-metal is not alloyed to an alloy, this means
that the metal or non-metal in question is not actively added.
[0012] In a first embodiment, the object of the present invention
is achieved by the use of a zinc wrought alloy having an Al content
of from 5% by weight to 12% by weight, a Cu content of from 0.1% by
weight to 4% by weight, an Mg content of from 0.001% by weight to
0.05% by weight, wherein Zn is the balance to 100%, for preparing
forgings, turned parts, locks, screw connections, locking
cylinders, sleeves, fittings, pressed parts, pneumatic parts,
hydraulic parts, mountings, valves and/or ball valves.
[0013] If percentages are stated with respect to components
contained in the alloy in the present application, they are percent
by weight unless explicitly stated otherwise. In particular, no
further metals in addition to the metals mentioned are alloyed with
the alloy when it is prepared. More preferably, the alloy according
to the invention is free of zirconium.
[0014] Surprisingly, it has been found that the surface coating of
the parts prepared can be improved by limiting the aluminum content
to a maximum of 12% by weight. Other zinc wrought alloys (as
disclosed, for example, in EP 2675971--"Accessory consisting of a
lock accessory") have poorer coating properties. Surprisingly, an
improved adhesion strength and density of the coating could be
achieved by limiting the aluminum content in
zinc-aluminum-copper-magnesium alloys. This results in an improved
corrosion protection. All methods of surface treatment (such as
electroplating, PVD, CVD, passivation, coating, cathodic dip
painting, powder coating) are suitable for the present invention
without limitation.
[0015] Alloying with lead is not necessary. Preferably, lead is not
alloyed. Preferred is a Pb content in the alloy according to the
invention of <0.003% by weight, which is present in the alloy as
an impurity of zinc, in particular, but not as an additional alloy
component.
[0016] Particularly preferred is the use of a zinc wrought alloy
with a content of Al of from 5% to 12% by weight, preferably from
5% to 8% by weight, or from 9% to 12% by weight. These ranges are
preferred because all alloys are supereutectic therein, and there
is a first beta phase in the crystal structure. This beta phase is
preferred because it recrystallizes at room temperature very slowly
(>10 years).
[0017] Particularly preferred is the use of a zinc wrought alloy
with a content of Cu of from 0.1% by weight to 2.5% by weight,
especially from 0.5% by weight to 1.5% by weight. This range is
preferred to achieve the maximum mechanical strength, and to avoid
the risk of forming of a brittle epsilon phase in the crystal
structure.
[0018] Particularly preferred is the use of a zinc wrought alloy
with a content of Mg from 0.003% to 0.05% by weight, especially
from 0.003% by weight to 0.03% by weight. This range serves as a
precaution to prevent intercrystalline corrosion by the residual
traces of impurities.
[0019] The zinc wrought alloy used according to the invention may
further contain silicon. If it contains silicon, the content of
silicon in the alloy is in particular within a range of from 0.005%
by weight to 0.02% by weight. The silicon content is determined by
the selection of Al content, because it is an impurity in
aluminum.
[0020] It has been found that an alloy having an Al content of from
5% to 8% by weight, a Cu content of from 0.5% by weight to 1.5% by
weight, an Mg content of from 0.003% by weight to 0.05% by weight,
with zinc as the balance to reach 100% by weight, has particularly
good coating properties.
[0021] Particularly preferred according to the invention is a zinc
wrought alloy with an Al content of from 9% by weight to 12% by
weight, a Cu content of from 0.5% by weight to 1.5% by weight, an
Mg content of from 0.003% by weight to 0.05% by weight, with zinc
as the balance to reach 100% by weight. Corresponding alloys have
good coating properties. Therefore, such an alloy, or the use
thereof, is preferred.
[0022] In addition to the mentioned components, an alloy according
to the invention may further comprise up to 1% by weight titanium
(Ti). The titanium content of at most 1% in the zinc alloy is
limited by the solubility of titanium. Titanium is an extremely
effective alloy element, strongly affecting the microstructure and
the mechanical properties of the alloy already in the ppm range
because of its lattice structure. Corresponding alloys have an
improved machinability.
[0023] In addition to the mentioned components, the alloy used
according to the invention may also comprise impurities resulting
from the fact that these components are derived from recycling.
However, for the usual sources of the components, these are not
critical. Common impurities are the presence of Cd, Pb, Sn and/or
Fe. Preferably, these impurities are contained only in very small
amounts, so that they do not adversely affect the properties of the
alloy according to the invention. Therefore, preferred is a Pb
content of <0.003% by weight, and/or a Cd content of <0.003%
by weight, especially <0.0005% by weight, and/or an Sn content
of <0.001% by weight, especially of <0.0005% by weight,
and/or an Fe content of <0.05% by weight. Preferably, the
content of all stated impurities is below the mentioned upper
limits. Preferably, the content of all impurities is 0.07% by
weight or less.
[0024] Thus, the present invention relates to the use of the zinc
wrought alloy according to the invention for preparing semifinished
products and articles with improved coating properties. When
reference is made to the alloy according to the invention in the
present application, this is supposed to mean the alloy used
according to the invention.
[0025] Further included according to the invention is a
semifinished product or article obtainable by processing the zinc
wrought alloy according to the invention. This semifinished product
may be, in particular, a billet, an extruded section, a drawn
section, a wire, a strip, a powder, or a pressure die-cast alloy.
In particular, the article may be a forging, turned part, lock,
screw connection, locking cylinder, sleeve, fitting, pressed part,
pneumatic part, hydraulic part, mounting, valve or ball valve.
[0026] The semifinished product according to the invention,
especially the billet, can be prepared, for example, by casting the
zinc wrought alloy according to the invention into a mold. When the
alloy according to the invention has been formed into a billet
shape, for example, a section can be prepared therefrom by
reshaping by means of extrusion.
[0027] Further, the zinc wrought alloy according to the invention
can be processed by different reshaping methods. Such reshaping
methods include, in particular, rolling, forging and drawing.
Further, the semifinished products prepared from the zinc wrought
alloy according to the invention are processed further, for
example, into forgings, turned parts, locks, screw connections,
locking cylinders, sleeves, fittings, pressed parts, pneumatic
parts, hydraulic parts, mountings, valves and ball valves using
different processing methods. These articles according to the
invention are excellently suitable for being subjected to coating
methods.
[0028] The zinc wrought alloy according to the invention and the
articles prepared therefrom exhibit improved coating properties as
compared to conventional ZnAl/ZnAlCu/ZnAlCuMg alloys. These include
an improved adhesion and density of the coating on the substrate
material, and an improved corrosion resistance resulting therefrom,
which shows in the results in a salt spray mist test, condensation
water test, or thermal shock test.
[0029] The requirement for the invention is to enhance the
coatability and corrosion resistance. This object was achieved by
limiting the aluminum content in the alloy according to the
invention to a maximum of 12% by weight. There may be mentioned, in
particular, the coating properties that were significantly improved
thereby, so that an improved corrosion resistance can be achieved.
In the experiments, it is found that this can be achieved by
reducing the aluminum content.
[0030] The prepared products comprising and, in particular, made of
the zinc alloy according to the invention have an excellent
processability, especially coatability, caused by the optimum
composition of zinc, aluminum, copper and magnesium.
[0031] In the following Examples, the present invention is further
explained in a non-limiting way, and advantages over the prior art
are pointed out.
EXAMPLES
[0032] A qualification of zinc wrought alloys is usually affected
by means of the following five methods delimited from one
another:
Method 1 (Reshaping Method):
[0033] The billet was heated at 250.degree. C. in an oven.
Thereafter, the billet was extruded into a round section. Further,
the extruded round rod was drawn to a final dimension of 20 mm. The
testing requirements are considered to be met if no signs of
surface cracks or blisters have formed.
Method 2: (Layer Thickness Test by Polished Section Analysis):
[0034] As a second method, a microscopic examination of the coating
by analogy with DIN EN ISO 1463:2004-08 is performed. This serves
for testing the layer thickness and the bonding of the coating to
the substrate material. For this purpose, polished transverse
sections of the coated specimens are prepared. Thereupon, the
sections are embedded, ground and polished. For a differentiation
of the different microstructural components and the coating, the
surface of the specimen is etched with aqueous sodium hydroxide
(NaOH) solution. The testing requirements are considered to be met
if the coating has a good bonding to the substrate material and
reaches the desired layer thickness.
Method 3 (Corrosion Resistance by Salt Spray Test):
[0035] According to DIN EN ISO 9227:2012, a salt spray test with a
sodium chloride solution having a neutral pH is performed. The
testing requirements are considered to be met if no corrosion in
the form of white rust occurs on the surface after 96 hours in the
salt spray test.
Method 4 (Condensation Water Test):
[0036] According to DIN EN ISO 6270-2:2016, a test with a
condensation water constant climate is performed. Thus, distilled
water is filled into the base tray of a suitable sealed chamber.
The chamber is heated at (40.+-.3) .degree. C., reaching a relative
humidity of about 100%. The test requirements are considered to be
met if no blistering or corrosion (in the form of white rust)
occurs on the surface of the specimen after 96 hours in a
condensation water chamber.
Method 5 (Thermal Shock Test):
[0037] In a thermal shock test by analogy with DIN EN ISO
2819:1995, the test specimen is stored at (220.+-.10) .degree. C.
for 30 minutes and then immediately quenched in water with a
temperature of 15.degree. C. to 25.degree. C. The test requirements
are considered to be met if no chipping or blistering of the
coating occurs.
[0038] Since corrosion resistance is presently in the focus, the
alloys according to the invention were analyzed under this aspect
and compared with prior art alloys. The compositions of the
comparative alloys are shown in Table 1. Table 2 shows the
compositions of the alloys according to the invention.
TABLE-US-00001 TABLE 1 Comparative materials Components Unit Zinc
alloy Aluminum % by weight 13-25 Copper % by weight 0.2-3.5
Magnesium % by weight <0.1 Lead % by weight <0.004 Zinc % by
weight balance
[0039] A zinc wrought alloy as described in EP 2 675 971 was used
as a comparative material (information in column "zinc alloy" in
Table 1).
[0040] From the following alloys according to the invention,
billets having a diameter of 135 mm were prepared, which served as
a starting point for the qualification:
TABLE-US-00002 TABLE 2 Alloys according to the invention Components
Unit Specimen 1 Specimen 2 Aluminum % by weight 5-8 9-12 Copper %
by weight 0.5-1.5 0.5-1.5 Magnesium % by weight 0.003-0.05
0.003-0.05
[0041] The above described tests were performed for testing the
corrosion resistance.
Results:
[0042] Before the coating process, the specimens were pretreated in
accordance with their alloy composition. Thereafter, the specimens
were coated with different systems and tested according to the
above-mentioned testing requirements. In the coating process, the
same process times were used for all specimens for direct
comparability.
[0043] For a clear evaluation of the specimens, a system with the
following legend is used: [0044] ++: requirements of the corrosion
test procedure are met particularly well [0045] +: requirements of
the corrosion test procedure are met [0046] 0: requirements of the
corrosion test procedure are met in part [0047] -: requirements of
the corrosion test procedure are not met
[0048] By way of example, the coating with a cyanidic Cu--Cu--Ni
system is shown in some detail.
Results of Method 2 (Layer Thickness Test by Polished Section
Analysis):
TABLE-US-00003 [0049] TABLE 3 Layer thickness test by polished
section analysis Copper [.mu.m] Nickel [.mu.m] Total [.mu.m]
Specimen 1 34 23 57 Specimen 2 20 25 45 Comparative material 12 13
26
TABLE-US-00004 TABLE 4 Evaluation of the specimens by means of
layer thickness results Specimen 1 ++ Specimen 2 ++ Comparative
material 0
[0050] Microscopic examinations of the specimens including
information of layer thickness are shown in FIG. 1. Please note
that the different copper layers cannot be distinguished in the
micrograph of the polished section.
[0051] Surprisingly, the results showed that specimen 1 and
specimen 2 exhibit a higher layer thickness as compared to the
comparative material. This shows that the present invention
achieves a higher deposition rate. This accelerates the process of
coating, which is an advantage. Further, a good bonding to the
substrate material can be seen in the polished section micrographs
of specimen 1 and specimen 2, while the comparative material in
part shows defects between the copper layer and the substrate
material.
Results of Method 3 (Corrosion Resistance by Salt Spray Test):
TABLE-US-00005 [0052] TABLE 5 Evaluation of specimens by means of
salt spray test Specimen 1 + Specimen 2 + Comparative material
0
[0053] The salt spray test showed that no corrosion (in the form of
white rust) has occurred on the surface of the specimens for
specimen 1 and specimen 2. Thus, the substrate material under the
coating was not attacked despite a highly stressing
environment.
Results of Method 4 (Condensation Water Test):
TABLE-US-00006 [0054] TABLE 6 Evaluation of specimens by means of
condensation water test Specimen 1 + Specimen 2 ++ Comparative
material 0
[0055] Micrographs of the specimens are shown in FIG. 2. With
specimen 1, a rough surface was formed, but on which no defects or
blisters could be identified. The surface of specimen 2 remained
surprisingly unchanged and showed neither roughening nor blisters.
The comparative material formed large blisters by the test. The
present invention met the testing requirements.
Results of Method 5 (Thermal Shock Test):
TABLE-US-00007 [0056] TABLE 7 Evaluation of specimens by means of
thermal shock test Specimen 1 + Specimen 2 + Comparative material
0
[0057] Micrographs of the specimens are shown in FIG. 3. The
results show that specimen 1 and specimen 2 showed no chipping or
blistering. Thus, the testing requirements are considered to be met
for the present invention. The comparative material in turn showed
blisters that were in part pronounced.
[0058] In the following, the other coating systems are evaluated in
summary
TABLE-US-00008 TABLE 8 General evaluation of the specimens
Comparative Coating Specimen 1 Specimen 2 material Cu--Cu--Ni
(cyanidic) + ++ 0 Cu--Cu--Ni (cyanide-free) + ++ 0
[0059] Surprisingly, the present invention had improved coating
properties as compared to the prior art. This was shown in the
different testing methods. The testing requirements were met in all
methods. The bonding of the coating to the substrate material was
good according to the requirements, and neither corrosion (in the
form of white rust) nor chipping nor blistering occurred on the
surface of the specimens. Further, the present invention
surprisingly showed an enhanced deposition rate and thus achieved
shorter process times. The particularly good test results of
specimen 2 are to be mentioned.
[0060] In addition, a more environment-friendly kind of coating is
surprisingly enabled by the present invention by means of
cyanide-free copper plating.
* * * * *