U.S. patent number 3,648,355 [Application Number 05/051,278] was granted by the patent office on 1972-03-14 for method for making an electric contact material.
This patent grant is currently assigned to Matsushita Electric Industrial Co., Ltd.. Invention is credited to Sankichi Shida, Tsunehiko Todoroki.
United States Patent |
3,648,355 |
Shida , et al. |
March 14, 1972 |
METHOD FOR MAKING AN ELECTRIC CONTACT MATERIAL
Abstract
Novel electrical contact materials are provided. The materials
are comprised of three bonded layers including a top layer of
palladium, an intermediate layer of a silver alloy and a
nickel-copper alloy spring layer.
Inventors: |
Shida; Sankichi (Nara,
JA), Todoroki; Tsunehiko (Osaka, JA) |
Assignee: |
Matsushita Electric Industrial Co.,
Ltd. (Kadoma, Osaka, JA)
|
Family
ID: |
12948461 |
Appl.
No.: |
05/051,278 |
Filed: |
June 30, 1970 |
Foreign Application Priority Data
|
|
|
|
|
Jul 2, 1969 [JA] |
|
|
44/53639 |
|
Current U.S.
Class: |
228/187; 29/874;
228/190; 228/199; 228/228; 403/179; 428/669; 428/673; 428/674;
428/929; 439/894 |
Current CPC
Class: |
H01H
1/023 (20130101); B32B 15/018 (20130101); Y10S
428/929 (20130101); Y10T 428/12896 (20150115); Y10T
428/12903 (20150115); Y10T 428/12868 (20150115); Y10T
403/35 (20150115); Y10T 29/49204 (20150115) |
Current International
Class: |
B32B
15/01 (20060101); H01H 1/023 (20060101); H01H
1/02 (20060101); B23k 031/02 () |
Field of
Search: |
;29/475,504,194,199,471.1,472.3,480,471.7 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Campbell; John F.
Assistant Examiner: Lazarus; Richard Bernard
Claims
The embodiments of the invention in which exclusive property or
privilege is claimed are defined as follows:
1. A method for making an electric contact material comprising
heating a combination of a palladium alloy sheet and a silver alloy
sheet having a bonding layer inserted therebetween under pressure
at a first bonding temperature of 720.degree. to 850.degree. C.,
whereby said bonding layer diffuses into both said palladium alloy
sheet and said silver alloy sheet to form a two layer bonded sheet,
said palladium alloy sheet being in a composition consisting
essentially of a main ingredient of palladium, a first additive
ingredient selected from the group consisting of nickel, cobalt and
copper and a second additive ingredient selected from the group
consisting of silver and copper and said bonding layer consisting
essentially of a member selected from the group consisting of a
copper layer and a combination of a copper layer and an indium
layer;
cooling said two layer bonded sheet to room temperature and
rolling;
heating a combination of the two layer bonded sheet and a
nickel-copper alloy sheet having another bonding layer inserted
therebetween under pressure at a second bonding temperature of
700.degree. to 830.degree. C. so as to form a three layer bonded
sheet having a nickel-copper alloy spring layer bonded to said two
layer bonded sheet;
cooling said three layer bonded sheet to room temperature; and
rolling the cooled three layer bonded sheet.
2. A method for making an electric contact material defined by
claim 1, wherein said silver alloy sheet consists essentially of 95
to 97 wt. percent of silver and 3 to 5 wt. percent of copper and
each of said bonding layer and said another bonding layer consists
essentially of a copper layer in a thickness of 20 to 50
microns.
3. A method for making an electric contact material defined claim
1, wherein said silver alloy sheet consists essentially of 60 to 94
wt. percent of silver and 6 to 40 wt. percent of copper and each of
said bonding layer and said another bonding layer consists of a
combination of a copper layer and an indium layer.
4. A method for making an electric contact material defined in
claim 3, said combination has a thickness of 20 to 50 microns
whereby a thickness ratio of said indium layer to said copper layer
ranges from 1:1 to 1:2.
5. A method for making an electric contact material defined by
claim 3, wherein said another bonding layer consists essentially of
a combination of an indium layer and a copper layer which is
adhered to said nickel-copper alloy sheet.
6. A method for making an electric contact material defined by
claim 1, wherein said three layer bonded sheet has the palladium
alloy top layer including 40 to 95 wt. percent of palladium.
7. A method for making an electric contact material defined by
claim 1, wherein said original palladium alloy sheet is in a
composition consisting essentially of 1 to 6 wt. percent of a metal
selected from the group consisting of nickel and cobalt, 2 to 39
wt. percent of silver and 60 to 95 wt. percent of palladium.
8. A method for making an electric contact material defined by
claim 1, wherein said original palladium alloy sheet is in a
composition consisting essentially of 1 to 6 wt. percent of a metal
selected from the group consisting of nickel and cobalt, 2 to 15
wt. percent of copper and 79 to 95 wt. percent of palladium.
9. A method for making an electric contact metal defined by claim
1, wherein said original palladium alloy sheet is in a composition
consisting essentially of 3 to 15 wt. percent of copper, 2 to 37
wt. percent copper, 2 to 37 wt. percent of silver and 60 to 95 wt.
percent of palladium.
10. A method for making an electric contact material defined by
claim 1, wherein said original silver alloy sheet is in a
composition consisting essentially of 60 to 96.8 wt. percent of
silver, 3 to 39.95 wt. percent of copper and 0.05 to 0.2 wt.
percent of phosphorous.
11. A method for making an electric contact material defined by
claim 1, wherein said original silver alloy sheet is in a
composition consisting essentially of 60 to 96.5 wt. percent of
silver, 3 to 37 wt. percent copper and 0.5 to 3 wt. percent of
nickel.
12. A method for making an electric contact material defined by
claim 1, wherein said original nickel-copper alloy sheet is in a
composition consisting essentially of 63.0 to 70.0 wt. percent of
nickel, less than 2.5 wt. percent of iron, less than 1.25 wt.
percent of manganese, less than 0.5 wt. percent of silicon, less
than 0.024 wt. percent of sulfur, less than 0.08 wt. percent of
carbon and the remainder copper.
13. A method for making an electric contact material defined by
claim 1, wherein the rolled three layer bonded sheet has the
palladium alloy top layer in a thickness of 0.5 to 5 microns.
Description
This invention relates to a method for making an electric contact
material and particularly said electric contact material is in a
three layer bonded sheet including a palladium alloy top layer, a
silver alloy intermediate layer and nickle-copper alloy spring
layer.
The advanced industry has required increasingly a more reliable
electric contact material. The reliable electric contact material
must be provided with a high resistance to chemical corrosion such
as sulfurization and mechanical wear as well as a low contact
resistance and a high spring action.
There have been paid various efforts in obtaining the reliable
electric contact at a cost as low as possible. However, the
electric contacts available commercially at the present are not
entirely satisfactory with these requirements.
An object of this invention is to provide a method for making an
electric contact material characterized by low contact resistance
and excellent mechanical properties such as high modulus of
elasticity and high fatigue strength. Another object of this
invention is to provide a method for making an electric contact
material in a three layer bonded sheet including a palladium alloy
top layer, a silver alloy intermediate layer and nickle-copper
alloy spring layer.
These and other objects of this invention will be apparent upon
consideration of the following detailed description taken together
with accompanying drawings wherein:
FIG. 1 is a cross sectional view of a three layer bonded sheet
according to the present invention,
FIGS. 2A through 2D are a schematic illustration of production
steps of a three layer bonded sheet of FIG. 1,
FIGS. 3A through 3D are another schematic illustration of
production steps of a three layer bonded sheet of FIG. 1,
FIG. 4 is variations of contact resistance with palladium content
of palladium-silver alloy after sulfurization.
A method for making an electric contact material according to the
present invention comprises the following steps:
1. A step for heating a combination of a palladium alloy sheet and
a silver alloy sheet having a bonding layer inserted therebetween
under pressure at a first bonding temperature of 720.degree. to
850.degree. C., whereby said bonding layer diffuses into both said
palladium alloy sheet and said silver alloy sheet to form a two
layer bonded sheet and rolling the cooled two layer bonded
sheet.
2. A second step for heating a combination of said two layer bonded
sheet and a nickel-copper alloy sheet having another bonding layer
inserted therebetween under pressure at a second bonding
temperature of 700.degree. to 830.degree. C., so as to form a three
layer bonded sheet having a nickel-copper alloy spring layer bonded
to said two layer bonded sheet.
3. A third step for cooling said three layer bonded sheet to room
temperature and rolling the cooled three layer bonded sheet into an
electric contact material having a desired thickness.
Before proceeding with the detailed description of the present
invention, the construction of electric contact material
contemplated by the invention will be explained with reference to
FIG. 1. Reference character 10 designates, as a whole, an electric
contact material consisting essentially of a three layer bonded
sheet which has the following layers integrated together in the
order of top below; a palladium alloy top layer 1, a silver alloy
intermediate layer 2 and a nickel-copper alloy spring layer 3.
These layers 1, 2 and 3 are bonded in a method described in detail
hereinafter. The palladium alloy top layer 1 is to protect the
silver alloy intermediate layer 2 from the sulfurization and
oxidation during storage and operation. The nickel-copper alloy
spring layer 3 is to provide the electric contact material 10 with
spring action. The silver alloy intermediate layer 2 has a low
electric resistance and acts as an electric contact part. A
composition and thickness of each of three layers 1, 2 and 3 will
be explained hereinafter.
Referring to FIGS. 2A through 2D, a method for making an electric
contact material according to the present invention will be
explained. The method comprises a combination of following
steps:
1. A step for heating a combination 20 of a palladium alloy sheet
11 and a silver alloy sheet 12 having a bonding layer 14 inserted
therebetween under pressure at a first bonding temperature of
720.degree. to 850.degree. C. An operable pressure range from 5 to
20 kg./cm..sup.2 and can be applied by any suitable and available
method during heating. For example, the combination 20 is penched
by two thick stainless steel plates which are clamped strongly at
the four corners by bolts. After heating for given time which
depends upon the size of the combination 20, the combination 20 is
converted into a two layer bonded sheet 30 consisting of a
palladium alloy top layer 1 and silver alloy intermediate layer 4.
The bonding layer 14 diffuses away through the palladium alloy
sheet 11 and the silver alloy sheet 12 during the heating and
disappears when cooled to room temperature. As a result the
compositions of the palladium alloy top layer 1 and the silver
alloy intermediate layer 4 are different from the original
palladium alloy sheet 11 and the original silver alloy sheet 12,
respectively due to the diffusion of bonding layer 14.
The palladium alloy sheet 11 is in a composition consisting
essentially of a main ingredient of palladium, a first additive
ingredient selected from the group consisting of nickel, cobalt and
copper and a second additive ingredient selected from the group
consisting of silver and copper. The bonding layer 14 consisting
essentially of a member selected from the group consisting of a
copper layer and a combination of a copper layer and an indium
layer. The bonding layer 14 can be formed by any suitable and
available methods such as vacuum deposition or electrochemical
deposition of bonding material on either palladium alloy sheet 11
or silver alloy sheet 12. Another method is to insert bonding
material foil between the palladium alloy sheet 11 and silver alloy
sheet 12.
2. A second step for heating a combination 40 of a two layer bonded
sheet 30 and a nickel-copper alloy sheet 13 having another bonding
layer 15 inserted therebetween under pressure at a second bonding
temperature of 700.degree. to 830.degree. C. An operable pressure
range from 30 to 70 kg./cm..sup.2 and can be applied in a way
similar to that of a first step (1). Said another bonding layer 15
has a composition essentially the same as that of said bonding
layer 14 and can be formed in a manner similar to that of the
bonding layer 14. After heating for given time which depends upon
the size of the combination 40, the combination 40 is converted
into a three layer bonded sheet 50 consisting of a palladium alloy
top layer 1, a silver alloy intermediate layer 2 and a
nickel-copper alloy spring layer 3. The another bonding layer 15
diffuses away through the silver alloy layer 4 and the
nickel-copper alloy sheet 13 during the heating and disappears when
cooled to room temperature. As a result, the composition of the
silver alloy intermediate layer 2 and the nickel-copper alloy
spring layer 3 are different from the original silver alloy
intermediate layer 4 and the original nickel-copper alloy sheet 13,
respectively due to the diffusion of another bonding layer 15.
A heating atmosphere on bonding step (1) and (2) must be
non-oxidizing atmosphere such as nitrogen gas, argon gas or vacuum
for prevention of oxidation of electric contact material. It is
necessary that the second boiling temperature is always lower than
the first bonding temperature.
3. A third step for rolling the cooled three layer bonded sheet 50
into an electric contact material 10 having a desired thickness.
The suitable annealing temperature of the three layer bonded sheet
50 during cold rolling is 620.degree. to 670.degree. C. for 1 hour.
This method makes it possible to form a fine electric contact
material characterized by the strong bonding strength between each
two layers.
Operable composition for the silver alloy sheet 12 consists
essentially of 60 to 97 wt. percent of silver and 3 to 40 wt.
percent of copper. Copper, indium, lead, tin, zinc, etc. and their
combinations are useful for bonding layer 14. In view of the
electric contact characteristics, copper and indium are preferable.
When the silver alloy sheet 12 is in a composition of 95 to 97 wt.
percent of silver and 3 to 5 wt. percent of copper, each of two
bonding layers 14 and 15 is preferably composed of a copper layer
in view of the solidus temperature of silver alloy sheet 12.
When the silver alloy sheet 12 is in a composition of 60 to 94 wt.
percent of silver and 6 to 40 wt. percent of copper, each of two
bonding layers 14 and 15 must be composed of a combination of a
copper layer 14-1 or 15-1 and indium layer 14-2 or 15-2 in view of
the eutectic temperature of silver alloy sheet 12 as shown in FIGS.
3A through 3D in which similar characters designate components
similar to those of FIGS. 2A through 2D. It has been discovered
according to the present invention that a higher bonding strength
can be obtained by facing the copper layer 15-1 to the
nickel-copper alloy sheet 13. A combination of a copper layer 14-1
or 15-1 and an indium layer 14-2 or 15-2 reacts with silver-copper
alloy to form silver-copper-indium eutectic composition having a
melting point lower than that of silver-copper alloy.
A thickness of the two bonding layers 14 and 15 less than 20
microns results in a low bonding strength. The bonding layer 14 and
15 thicker than 50 microns causes larger amounts of copper to
diffuse to a surface of the palladium alloy sheet 11 during heating
at the first bonding temperature. The diffused copper on the
surface impairs the electric contact characteristics. The bonding
layer 15 thicker than 50 microns fails to form a complete eutectic
melt and remains a part of copper unmelted. This impairs the
bonding strength. Operable thickness of the two bonding layers 14
and 15 must be 20 to 50 microns.
In the combination of copper layer 14-1 or 15-1 and indium layer
14-2 or 15-2, a thickness ratio of the copper layer to indium layer
preferably ranges from 1:1 to 1:2. An indium layer thicker than the
ratio 1:1 produces a large amount of electric melt at an interface
between the palladium alloy sheet 11 and the silver alloy sheet 12
or between the two layer bonded sheet 30 and the nickel-copper
alloy sheet 13. The large amount of eutectic melt leaks away from
the interface and prevents a formation of smooth interface. This
also impairs the bonding strength.
A foresaid palladium alloy top layer 1 is to protect the silver
alloy intermediate layer 2 from a chemical erosion such as
sulfurization. An operable thickness of said palladium alloy top
layer 1 is 0.5 to 5 microns. In view of the sulfurization, and
mechanical wear it is necessary that the palladium alloy top layer
1 has 40 to 95 wt. percent of palladium included therein when the
electric contact material 10 is finally achieved. As shown in FIG.
4, the sulfurization limit is 40 wt. percent of palladium for
palladium-silver alloy in view of the contact resistance. The
necessity can be satisfied by employing a palladium alloy sheet 11
in a composition listed in table 1.
Addition of 1 to 6 wt. percent of nickel or cobalt is effective in
strengthening the palladium alloy top layer 1. Nickel or cobalt
more than 6 wt. percent is apt to segregate and impair the
ductility and workability of palladium alloy sheet 11.
Palladium-nickel or palladium-cobalt alloy without silver and/or
copper causes silver and/or copper to diffuse irregularly from the
silver alloy sheet 12 and the bonding layer 14. The irregular
diffusion results in a dappled surface of palladium alloy top layer
1. An addition of copper or silver of at least 2 wt. percent can
prevent the irregular diffusion of silver and/or copper in the
palladium alloy top layer 1. Upper limit of copper addition is 15
wt. percent in view of the electric contact characteristics. Upon
limit of silver addition is 39 wt. percent in view of the
sulfurization of palladium alloy top layer 1.
Both copper and silver addition to palladium without nickel or
cobalt is also operable. In view of mechanical properties, electric
contact characteristics and sulfurization, operable composition is
shown by a sample No. 5 of table 1.
Silver alloys in a composition of table 2 are advantageous in view
of mechanical properties and electric contact characteristics as
intermediate layer. Copper less than 3 wt. percent does not provide
the intermediate layer 2 with sufficient mechanical properties.
Copper above 40 wt. percent has no effect to increase the
mechanical properties and impairs electric contact
characteristics.
In view of the elasticity, fatigue strength and ductility, a
composition listed in table 3 is useful for nickel-copper alloy
sheet which forms finally into a spring layer. The carbon content
in the nickel-copper alloy is important factor for the elasticity.
Carbon content must be less than 0.08 wt. percent. Ductility and
fatigue strength are damaged when carbon content is higher than
0.08 wt. percent.
The thickness of palladium alloy top layer 1 of rolled three layer
bonded sheet 10 is 0.5 to 5 microns. The effect of palladium alloy
top layer 1 against sulfide formation is not sufficient when
thickness of palladium alloy top layer 1 is less than 0.5 microns.
Above 5 microns, other convenient methods serve the purpose of
making this type of electric contact material. ##SPC1##
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TABLE 2
Composition of silver alloy sheet
Sample No. 1 2
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60 .about. 96.8 wt. % Ag 60.about.96.5 wt. % Ag 3.about.39.95 wt. %
Cu 3.about.37 wt. % Cu 0.05.about.0.2 wt. % P 0.5.about.3 wt. % Ni
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TABLE 3
Composition of nickel-copper alloy sheet
63.0 70.0 wt. % Ni
less than 2.5 wt. % Fe
less than 1.25 wt. % Mn
less than 0.5 wt. % Si
less than 0.024 wt. % S
less than 0.08 wt. % C
remainder Cu
EXAMPLE 1
A three layer electric contact material such as shown in FIG. 1 was
made by following steps. Referring to FIG. 3, a palladium alloy
sheet 11 was in a composition of 85 wt. percent of palladium, 12
wt. percent of silver and 3 wt. percent of nickel and a silver
alloy sheet 12 was in a composition of 85 wt. percent of silver, 13
wt. percent of copper and 2 wt. percent of nickel. Original
thicknesses of the palladium alloy sheet 11 and the silver alloy
sheet 12 were 0.3 and 4.2 mm. respectively. Both sheets were
cleaned on their surfaces to remove gross contaminations by a usual
manner. Then a copper layer 14-1 of 20 microns thick and an indium
layer 14-2 of 20 microns were electro-chemically deposited on the
palladium alloy sheet 11 and silver alloy sheet 12 respectively. A
combination 20 was penched under pressure of about 10 kg./cm..sup.2
by two thick stainless steel plates which were clamped strongly at
the four corners by bolts so that electro-chemically deposited
layers were faced closely to each other. The penched combination
was held at 750.degree. C. for 30 minutes in vacuum (10.sup.-.sup.2
mm. Hg). Thus, the combination 20 was converted into a two layer
bonded sheet 30 of 1 mm. thick after three repetitions of a cycle
of annealing at 550.degree. C. for 30 minutes and cold-rolling of
40 percent reduction.
A nickel-copper alloy sheet 13 of 9 mm. thick was cleaned on its
surface. A copper layer 15-1 of 20 microns thick was
electro-chemically deposited on the nickel-copper alloy sheet 13 as
shown in FIG. 3c. An indium layer 15-2 of 20 microns thick was
electro-chemically deposited on the silver alloy intermediate layer
4. The combination 40 was penched in a way similar to that of first
step under pressure of about 50 kg./cm..sup.2 and held at
700.degree. C. for 30 minutes in vacuum (10.sup.-.sup.2 mm.
Hg).
Thus, three layer bonded sheet 50 was converted into an electric
contact material 10 of 0.15 mm. thick after six repetitions of a
cycle of annealing at 650.degree. C. for 40 minutes and
cold-rolling. The rolling process was followed by the annealing
process every time when thickness of the three layer bonded sheet
50 was 5 mm., 2.4 mm., 1.2 mm., 0.6 mm., and 0.3 mm. Final
reduction of thickness was 50 percent and the palladium alloy top
layer 1 was in a thickness of about 1.5 micron by a microscopic
examination. The palladium content of the surface of the palladium
alloy top layer 1 was determined to be above 40 wt. percent by
using microanalyzer. Other elements were mainly silver, copper and
nickel. Indium was detected as trace.
Table 4 shows the mechanical properties of so produced electric
contact material. The electric contact material was subjected to a
sulfurization test shown by table 4. After testing, the electric
contact material had a contact resistance of 0.024 as shown in
table 4. The sulfurization test was carried out by holding the
electric contact material at 85.degree. C. for 100 hours in air
including 100 p.p.m. of H.sub.2 S. The contact resistance was
measured in the following manner. A gold electrode having a
spherical surface at the end was brought into against a contact
with the surface of electric contact material under pressure of 20
g. A direct current of 10 ma. was designed to flow from the GOLD
electrode through the contact area to the electric contact
material. The potential drop across the gold electrode and the
electric contact material was measured by an electronic
galvanometer and was calculated into a contact resistance.
EXAMPLE 2
Example 2 is substantially the same as example 1 and was made by
the method described in example 1 except that a palladium alloy
sheet 11 was in a composition of 95 wt. percent of palladium, 2 wt.
percent of silver and 3 wt. percent of cobalt and that a silver
alloy sheet 12 was in a composition of 60 wt. percent of silver, 37
wt. percent of copper and 3 wt. percent of nickel.
Table 4 shows the mechanical properties and contact resistance
after sulfurization test of resultant electric contact
material.
EXAMPLE 3
Example 3 is substantially the same as example 1 and was made by
the method described in example 1. Example 3 differs from example 1
in the following:
A palladium alloy sheet 11 was in a composition of 84 wt. percent
of palladium, 15 wt. percent of copper and 1 wt. percent of nickel
and silver alloy sheet 12 was in a composition of 93 wt. percent of
silver, 6 wt. percent of copper and 1 wt. percent of nickel. Each
of bonding layers 14 and 15 was a combination of copper and 30
microns thick and indium of 15 microns thick.
Table 4 shows the mechanical properties and contact resistance
after sulfurization test of resultant electric contact
material.
EXAMPLE 4
Example 4 is substantially the same as example 1 and was made by
the method described in example 1. Example 4 differs from example 1
in the following:
A palladium alloy sheet 11 was in a composition of 60 wt. percent
of palladium, 34 wt. percent of silver and 6 wt. percent of nickel
and was in an original thickness of 1.35 mm. A silver alloy sheet
12 was in a composition of 60 wt. percent of silver, 39.95 wt.
percent of copper and 0.05 wt. percent of phosphorous and was in an
original thickness of 3.15 mm.
Table 4 shows the mechanical properties and contact resistance
after sulfurization test of resultant electric contact material and
the palladium alloy top layer 1 was in a thickness of about 5
microns by a microscopic examination.
EXAMPLE 5
Example 5 is substantially the same as example 1 and was made by
the method described in example 1. Example 4 differs from example 1
in the following:
A palladium alloy sheet 11 was in a composition of 75 wt. percent
of palladium, 15 wt. percent of copper and 6 wt. percent of cobalt
and was in an original thickness of 1.35 mm. A silver alloy sheet
12 was in a composition of 85 wt. percent of silver, 13 wt. percent
of copper and 2 wt. percent of nickel and was in an original
thickness of 3.15 mm. Each of bonding layers 14 and 15 was a
combination of copper of 25 microns thick and indium of 25 microns
thick.
Table 4 shows the mechanical properties and contact resistance
after sulfurization test of resultant electric contact
material.
EXAMPLE 6
Example 6 is substantially the same as example 1 and was made by
the method described in example 1. Example 6 differs from example 1
in the following:
A palladium alloy sheet 11 was in a composition of 60 wt. percent
of palladium, 25 wt. percent of silver and 15 wt. percent of copper
and was in an original thickness of 1.2 mm. A silver alloy sheet 12
was in an original thickness of 3.3 mm. Each of bonding layers 14
and 15 was a combination of copper and 10 microns thick and indium
of 10 microns thick.
Table 4 shows the mechanical properties and contact resistance
after sulfurization test of resultant electric contact
material.
EXAMPLE 7
This example is substantially the same as example 1. A palladium
alloy sheet 11 was in a composition of 60 wt. percent of palladium,
39 wt. percent of silver and 1 wt. percent of cobalt, and was in an
original thickness of 0.6 mm. A silver alloy sheet 12 was in a
composition of 93 wt. percent of silver, 6 wt. percent of copper
and 1 wt. percent of nickel and was in an original thickness of 8.4
mm.
After cleaning on their surfaces, a copper layer 14-1 of 20 microns
thick and an indium layer 14-2 of 20 microns thick were
electro-chemically deposited on the palladium alloy sheet 11 and
silver alloy sheet 12 respectively. Then a combination 20 was
bonded at 720.degree. C. for 30 minutes in the same manner of
example 1 and was converted into a two layer bonded sheet 30 of 1.2
mm. thick after two repetitions of a cycle of annealing at
550.degree. C. for 20 minutes and cold-running of about 65 percent
reduction.
A nickel-copper alloy sheet 13 of 10.8 mm. thick was cleaned on its
surface. A copper layer 15-1 of 20 microns thick was
electro-chemically deposited on the nickel-copper alloy sheet 13.
An indium layer 15-2 of 20 microns thick was electro-chemically
deposited on the silver alloy intermediate layer 4. A combination
40 was bonded at 700.degree. C. for 30 minutes in the same manner
of first step and was converted into an electric contact material
10 of 0.15 mm. thick after four repetitions of a cycle of annealing
at 650.degree. C. for 30 minutes and cold-rolling. The rolling
process was followed by the annealing process every time when
thickness of the three layer bonded sheet 50 was 9.6 mm., 2.4 mm.
and 0.6 mm. Final reduction of thickness was 75 percent.
Table 4 shows the mechanical properties of so produced electric
contact material. After sulfurization test carried out similarly to
example 1, the electric contact material had a contact resistance
of 0.038 as shown in table 4.
EXAMPLE 8
Example 8 is substantially the same as example 1 and was made by
the method described in example 7 except that a palladium alloy
sheet 11 was in a composition of 60 wt. percent of palladium, 37
wt. percent of silver and 3 wt. percent of copper and that silver
alloy sheet 12 was in a composition of 60 wt. percent of silver, 37
wt. percent of copper and 3 wt. percent of copper and 3 wt. percent
of nickel.
Table 4 shows the mechanical properties and contact resistance
after sulfurization test of resultant electric contact
material.
EXAMPLE 9
Example 9 is substantially the same as example 1 and was made by
the method described in example 7 except that a palladium alloy
sheet 11 was in a composition of 84 wt. percent of palladium, 15
wt. percent of copper and 1 wt. percent of cobalt and that a silver
alloy sheet 12 was in a composition of 94 wt. percent of silver,
5.5 wt. percent of copper and 0.5 wt. percent of nickel.
Table 4 shows the mechanical properties and contact resistance
after sulfurization test of resultant electric contact
material.
EXAMPLE 10
Example 10 is substantially the same as example 1 and was made by
the method described in example 7. Example 3 differs from example 7
in the following:
A palladium alloy sheet 11 was in a composition of 95 wt. percent
of palladium, 2 wt. percent of copper and 3 wt. percent of nickel
and was in an original thickness of 0.2 mm. A silver alloy sheet 12
was in an original thickness of 8.8 mm.
Table 4 shows the mechanical properties and contact resistance
after sulfurization test of resultant electric contact material and
the palladium alloy top layer 1 was in a thickness of about 0.5
microns by a microscopic examination.
EXAMPLE 11
This example is substantially the same as example 1. Referring to
FIG. 2, a palladium alloy sheet 11 was in a composition of 95 wt.
percent of palladium, 2 wt. percent of silver and 3 wt. percent of
nickel and was in an original thickness of 0.6 mm. A silver alloy
sheet 12 was in a composition of 96.5 wt. percent of silver, 3 wt.
percent of copper and 0.5 wt. percent of nickel and was in an
original thickness of 8.4 mm. After cleaning on their surfaces, a
copper layer 14 of 20 microns thick was electro-chemically
deposited on the silver alloy sheet 12 and a combination 20 was
penched in the same manner of example 1 so that the copper layer 14
and the palladium alloy sheet 11 were faced closely to each other.
The penched combination was held at 850.degree. C. for 30 minutes
in vacuum (10.sup..sup.- 2 mm. Hg). Thus, the combination 20 was
converted into a two layer bonded sheet 30 of 1.2 mm. thick in the
same manner of example 7.
A nickel-copper alloy sheet 13 of 10.8 mm. thick was cleaned on its
surface. A copper layer 15 of 20 microns thick was
electro-chemically deposited on the nickel-copper alloy sheet 13.
The combination 40 was penched in the same manner of example 1 and
held at 830.degree. C. for 30 minutes in vacuum (10.sup..sup.- 2
mm. Hg).
Thus three layer bonded sheet 50 was converted into an electric
contact material 10 of 0.15 mm. thick in the same manner of example
7.
Table 4 shows the mechanical properties and contact resistance
after sulfurization test of resultant electric contact
material.
EXAMPLE 12
Example 12 is substantially the same as example 1 and was made by
the method described in example 11 except that a palladium alloy
sheet 11 was in a composition of 95 wt. percent of palladium, 2 wt.
percent of silver and 3 wt. percent of copper and that a silver
alloy sheet 12 was in a composition of 96,8 wt. percent of silver,
3 wt. percent of copper and 0.2 wt. percent of phosphorous.
Table 4 shows the mechanical properties and contact resistance
after sulfurization test of resultant electric contact
material.
EXAMPLE 13
This example is substantially the same as example 1. Referring to
FIG. 2, a palladium alloy sheet 11 was in a composition of 60 wt.
percent of palladium, 39 wt. percent of silver and 1 wt. percent of
nickel and a silver alloy sheet 12 was in a composition of 96.5 wt.
percent of silver, 3 wt. percent of copper and 0.5 wt. percent of
nickel. Original thickness of the palladium alloy sheet 11 and the
silver alloy sheet 12 were 1.2 and 3.3 mm. respectively. After both
sheets were cleaned on their surfaces, a copper layer 14 of 30
microns thick was electro-chemically deposited on the silver alloy
sheet 12 and a combination 20 was penched under pressure of about
20 kg./cm..sup.2 in the same manner of example 1 so that the copper
layer 14 and the palladium alloy sheet 11 were faced closely to
each other. The penched combination was held at 830.degree. C. for
30 minutes in vacuum (10.sup..sup.- 2 mm. Hg). Thus the combination
20 was converted into a two layer bonded sheet 30 of 1 mm. thick in
the same manner of example 1.
A nickel-copper alloy sheet 13 of 9 mm. thick was cleaned on its
surface. A copper layer 15 of 30 microns thick was
electro-chemically deposited on the nickel-copper alloy sheet 13.
The combination 40 was penched under pressure of about 70
kg./cm..sup.2 in the same manner of example 1 and held 830.degree.
C. for 30 minutes in vacuum (10.sup..sup.- 2 mm. Hg).
Thus three layer bonded sheet 50 was converted into an electric
contact material 10 of 0.15 mm. thick in the same manner of example
1 except that annealing condition was in a temperature of
620.degree. C. and was in a holding time of 1 hour.
Table 4 shows the mechanical properties and contact resistance
after sulfurization test of resultant electric contact
material.
EXAMPLE 14
Example 14 is substantially the same as example 1 and was made by
the method described in example 13 except that a palladium alloy
sheet 11 was in a composition of 60 wt. percent of palladium, 34
wt. percent of silver and 6 wt. percent of cobalt.
Table 4 shows the mechanical properties and contact resistance
after sulfurization test of resultant electric contact
material.
EXAMPLE 15
Example 15 is substantially the same as example 1 and was made by
the method described in example 13. Example 15 differs from example
13 in the following:
A palladium alloy sheet 11 was in a composition of 79 wt. percent
of palladium, 15 wt. percent of copper and 6 wt. percent of nickel
and a silver alloy sheet 12 was in a composition of 94 wt. percent
of silver, 6.5 wt. percent of copper and 0.5 wt. percent of nickel.
An annealing temperature of three layer bonded sheet 50 was
670.degree. C.
Table 4 shows the mechanical properties and contact resistance
after sulfurization test of resultant electric contact
material.
EXAMPLE 16
Example 16 is substantially the same as example 1 and was made by
the method described in example 13. Example 16 differs from example
13 in the following:
A palladium alloy sheet 11 was in a composition of 95 wt. percent
of palladium, 2 wt. percent of copper and 3 wt. percent of cobalt.
Copper layers 14 and 15 were in a thickness of 50 microns. An
annealing temperature of three layer bonded sheet 50 was
670.degree. C.
Table 4 shows the mechanical properties and contact resistance
after sulfurization test of resultant electric contact
material.
EXAMPLE 17
Example 17 is substantially the same as example 1 and was made by
the method described in example 13. Example 17 differs from example
13 in the following:
A palladium alloy sheet 11 was in a composition of 95 wt. percent
of palladium, 3 wt. percent of silver and 2 wt. percent of copper.
Copper layers 14 and 15 were in a thickness of 20 microns. An
annealing temperature of three layers bonded sheet 50 was
670.degree. C.
Table 4 shows the mechanical properties and contact resistance
after sulfurization test of resultant electric contact material.
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