CA1087235A - Silver-tin oxide composite electrical contact - Google Patents

Silver-tin oxide composite electrical contact

Info

Publication number
CA1087235A
CA1087235A CA288,044A CA288044A CA1087235A CA 1087235 A CA1087235 A CA 1087235A CA 288044 A CA288044 A CA 288044A CA 1087235 A CA1087235 A CA 1087235A
Authority
CA
Canada
Prior art keywords
contact
base portion
matrix
weight
copper
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
CA288,044A
Other languages
French (fr)
Inventor
Akira Shibata
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Chugai Electric Industrial Co Ltd
Original Assignee
Chugai Electric Industrial Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Chugai Electric Industrial Co Ltd filed Critical Chugai Electric Industrial Co Ltd
Application granted granted Critical
Publication of CA1087235A publication Critical patent/CA1087235A/en
Expired legal-status Critical Current

Links

Classifications

    • CCHEMISTRY; METALLURGY
    • C23COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23CCOATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C26/00Coating not provided for in groups C23C2/00 - C23C24/00
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01HELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H1/00Contacts
    • H01H1/02Contacts characterised by the material thereof
    • H01H1/021Composite material
    • H01H1/023Composite material having a noble metal as the basic material
    • H01H1/0237Composite material having a noble metal as the basic material and containing oxides

Abstract

ABSTRACT OF THE DISCLOSURE:

Composite electrical contact composed of a copper base portion clad with a contact portion of Ag-SnO alloy. The contact and base portions are fusion bonded by an interfacial alloy layer of Ag and Cu and an adjacent diffusion layer of Cu as the result of heat-treatment of the contact at the eutectic temperature of Ag and Cu.

Description

10~7235 This invention relates to an electrical contact composed of a base portion made from non~precious metals such as copper and clad with Ag-SnO alloy metals as a contact portion.
More particularly, this invention relates to a novel composite electrical contact of the kind mentioned above, in which the contact and base portions are fusion bonded to each other by means of a Ag-Cu interfacial alloy layer between the said two portions, and also by means of a diffusion layer of Cu which extends deeply into the matrix of the contact portion, said two layers having been produced by subjecting the composite electric contact for a comparatively short period of time to a temperature about or higher than the eutectic temperature of Ag and Cu, viz., 779C. This heat treatment, which would be comparable with liquid phase sintering production of a contact, not only produces the aforementioned layers which firmly affili-ate the contact and base portions, but also keeps an even dispersion of metallic oxides throughout the metrix of the contact portion of Ag-SnO. It shall be noted also that said heat treatment, which can be held after or simultaneously with binding of the base and contact portions by cold or hot press working, can release from the contact physical stresses produced in the contact by the press working.
It has been widely known to produce a clad electrical contact by clothing a base portion, such as for example a copper rivet-shape stem, with a thin plate of contact material made from silver-metallic oxides alloys, such as for example Ag-CdO alloys, by means of cold press. This clothing operation is firstly for improving physical and electrical properties of a composit electrical contact, especially its anti-welding property, by means of a Ag contact portion alloyed with metallic oxides, and secondly for minimizing the amount of expensive Ag in a contact and for increasing proportionately the amount 11~87235 of Cu in the contact.
The first point mentioned above as an advantage of the clothing operation is partly affirmative. ~lowever, the second point is questionable in its real merit. For example, in the case of a conventional contact of -the type having a Ag-CdO contact portion and a Cu base portion mechani.cally bonded to each other by cold press, the contact portion o~ten acci-dentally separates from the base por-tion when the former is only partially consumed (e.g. to only half its thickness).
This occurs because the binding force between the contact and base portions relies primarily upon mecha.nical or physical stress to cause the metal to become plastic and to flow between the two portions, and hence the resulting bond, which has been extrinsically weakened by metallic oxides existing about the interface between the two portions and pulverized by the cold press binding process, inherently is not strong enough to stand up against the different contact conditions which occur with the consumption of the contact. Assumed that the thickness or volume of the Ag-CdO contact portion is equal to the base portion, the life of this type of composite contact is only one fourth the life of a comparative solid contact, which is made wholly from Ag-CdO alloys, ~Ience, it is doubtful whether the saving of a half amount of Ag-CdO or Ag can compensate for the shortening of its brief life expectancy, when considered in the light of the expensive and laborious steps and processes that are involved in manufacturing such a bimetallic composite contact.
In order to eliminate -the drawbacks mentioned above, it has been tried by the present inventor to fusion bond a most conventional Ag-CdO alloy contact portion to a Cu base portion.
~his trial failed as no prior literature has disclosed a composite electrical contact composed of a contact portion of Ag-internal .

oxidized metal-and of a Cu base portion which are fusion or .~

diffusion bonded to each o-ther. In case of a composite electri-cal contact comprising a ~g-CdO contact portion, for example, such fusion bonding was found to be impossible, because cadmium oxides dispersed in the Ag matrix of the contact portion decomposed or sublimed at a temperature lower than the melting point of said Ag matrix metal, and the cadmium oxides therefore produced a segregation or barrier layer facing the inner surface of the Cu base portion, which is a detriment to a contact of this kind.
The applicant herein previously developed a specific Ag-SnO electrical contact material as disclosed in his U.S.
Patent N 3,933,~85. This specific electrical contact comprises an alloy having metal oxides precipitated therein as the result of internal oxidation, and being composed of about 5 to about 10% by weight of tin, and 1.0 to about 6% by weight of indium, the balance being silver. This alloy may contain a trace amount of less than 0.5% by weight of ferrous or alkali earth metals.
Applicant has also invented anoter specific Ag-SnO
electrical contact material comprising an alloy having metal oxides precipitated therein as the result of internal oxidation and being composed of 1.5 to 6% by weight of tin, 0.5 to 3%
by weight of indium, the total amount by weight of said tin and indium being less than 2 to 6%, a trace amount of less than 0.5% by weight ofiron family element, and the balance being silver.
The inventor has now found that the Ag-SnO electrical contact materials~ which he has invented as mentioned above, can advantageously be employed as a contact portion of a composite electrical contact composed of a contact portion of Ag-metal oxides, and a Cu basic portion, said two portions being fusion or diffusion bonded each to the other. This results from the findings that tin oxides of the aforementioned Ag-SnO alloys ~, 1~7235 are stable in an oxygen atmosphere and at a temperature up to about 2,000C, and sublime at the hoiling point of Ag, that these metal oxides are hard enough to withstand a butt press joining without producing undesireable pluverization of said oxides but instead producing the wedging of the oxides into the Cu base portion, which results in preventing the abutting surfaces of the base and contact portions from sliding trans-versely to the lonyitudinal axes of said two portions during the butt press joining operation, and also results in mechanical-ly strengthening the butt joint between the two portions, that a heat treatment of the portions at a temperature about the eutectic temperature of Ag and Cu, which produces the Cu diffusion into the Ag-SnO alloy matrix of the contact portion, does not adversely affect alloy structures of the base portion but works to release the two portions from stresses accompanied with the joining press work, and that the resultant bimetallic composite contact will have a useful life proportionate to the overall volume or thickness of the contact portion-i.e., will be useful until the contact portion has been substantially completely consumed.
It has been found also that among the aforementioned Ag-SnO electrical contact materials, those containing ferrous or alkali earth metals such as nickel and cobalt are most preferable as materials for the contact portion of the present invention, because such elements urge metal oxides to produce about spherical nuclei, causing the resultant Ag-SnO alloy to have a good elongation percentage, which is a prerequisite for the cold butt joîning of said alloy to a Cu base portion, utilizing plastic metallic flows therebetween.
For example, the following alloys, which were made by wires of 2mm in diameter and subjected to internal oxidation under oxidizing atmosphere at 750C. for 24 hours, have respective elollgatioll percentages as follows:
Sn 1.5% - In 0.5~ - Ni 0.1% - balance Ag (elongation ~ 11%) Sn 3% - In 1.3% - Ni 0.1~ - balance Ag (elongation 8%) Sn 4.2~ - In 1.8~ - Ni 0.1~ - Ag (elongation ~ 4%) I-lence, the present invention provides a heat-treated composite electrical contact composed of a base portion made from copper or copper-matrix alloys, and a contact portion clad to the base portion and made from an alloy having metal oxides pre-cipitated therein as the result of internal oxidation and being composed of 1.5 to 10% by weight of tin, 0.5 to 6% by weight of indium, and a trace amount of less than 0.5~ by weight of iron family element metals, the balance being silver; the contact and base portions are joined by an interfacial alloy layer composed of Ag and the matrix metal of the base portion, and the contact portion adjacent the alloy layer is diffused by the matrix metal of the base portion to a depth greater than the thickness of the alloy layer as the result of heat treatment of the contact for a brief period of time, and at a temperature about or higher than the eutectic temperature of Ag and the matrix metal of the base portion.
The heat treatment of the contact is preferably effected at a temperature higher than 779C for a period of less than 10 seconds.
The invention also provides a method of manufacturing a composite electrical contact, which comprises clading an in-ternally oxidized contact member, made from an alloy of 1.5-10%
by weight tin, 0.5-6.0% by weight indium, a trace amount of an iron family element metal and the balance silver, to a base member ' .' '' :' 1~87235 made from copper or copper-matrix alloys, and subjecting the composite contact to a temperature approximately equal to or higher than the eutectic temperature of Ag and the matrix metal of the base member, and for an interval sufEicient to cause the metal of the kase member to difEuse into the matrix of the contact member.
The following non-restrictive examples illustrate the invention.

A composite electrical contact of the rivet type (Sample A) was prepared from a contact portion of 5mm diameter and 0.5 mm. thickness made from a Ag-SnO alloy of Sn 5% - In 1.8% - Ni 0.3~-Ag, and a copper base portion having a base part of 5mm diameter and 1.0 mm thickness and an integral shank part of 2.5 mm diameter and 2.5 mm length by cladding the base with the contact portion by cold press butt joining. This Sample _ was heated at 800C for 10 seconds at atmospheric conditions. The Sample A thus heat-treated was cut and etched, and observed by an electron microscope at a magnification of x 2~00. There were observed an interfacial alloy layer of Ag-Cu of about 7/u around the boundary of the base and contact~

-5a-,~
, ~

1087Z3~
portions (and immediately adjacent the copper base), and a diffusion layer of Cu into the contact portion at a depth of about 51/u adjacent to the aforementioned Ag-Cu alloy layer, and at the side thereof remote from the Cu base or matrix.
It was also observed that the alloy structure of the contact portion, especially its metal oxides and the even distribution thereof, were not adversely affected by said Cu diffusion.
Sample B, having a construction similar tO the Sample _ but utilizing Ag-CdO 13%, was prepared without the above-noted heat-treatment.
Both samples A and B were subjected to switching tests of 50,000 cycles (AC 200V, 75A, for 0.6 second with a switching cycle of 3 seconds). Average loss of weight in Sample _ was 20.66 mg., while in Sample B 29.52 mg. Noticeable part of the contact portion of Sample B was broken off.

Sample A of Example 1, Sample C of dimensional structures same to the Sample A, but made wholly from Ag-CdO
13%, and a sample D of dimensions same as Sample _ but made wholly (i.e. both contact and base portions) from Ag-SnO alloy of Sn 5% - In 1.8% - Ni 0.3% - Ag, were tested for 2000 cycles under AC 200 V, 32A, 60 cycles per minute, contact force of 100 g. and opening force of 80g. Average hardness (HRF) of these three Samples when measured vertically from contact surfaces were 80 (Sample A), 107 (Sample C), and 110 (Sample D).
Times of welding and average force (g) are as follows.
Sample A 19 times 117g Sample C 21 times 138g Sample D 4 times 228g Contact resistances (m~ )of the samples are as follows:
At 1000 cycles -1~7235 Sample A 2.7 m Sample C 3.0 m,~
Sample D 3.2 m ,~
At 1500 cycles -Sample _ 1.9 mlZ
Sample C 3.8 m ~Z
Sample D 5.3 m At 2000 cycles Sample A 3.7 m Sample C 4.3 m ~z Sample D 4.5 m ~
Thus low contact resistance and good thermal dissipa-tion were observed in Sample _.
In the present invention instead of Cu and its alloy, A1 and Ni and their alloys can be employed also as a base portion. The heat-treatment of the contact for producing a fusion binding therein can, of course, be made simultaneously with a cold forging operation of the contact, for example by providing heat to cold forging dies.

Claims (3)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:
1. A heat-treated composite electrical contact composed of a base portion made from copper or copper-matrix alloys, and a contact portion clad to said base portion and made from an alloy having metal oxides precipitated therein as the result of internal oxidation and being composed of 1.5 to 10% by weight of tin, 0.5 to 6% by weight of indium, and a trace amount of less than 0.5% by weight of iron family element metals, the balance being silver;
said contact and base portions being joined by an interfacial alloy layer composed of Ag and the matrix metal of the base portion, and said contact portion, adjacent said alloy layer, being diffused by said matrix metal of the base portion to a depth greater than the thickness of said alloy layer as the result of heat treatment of the contact for a brief period of time, and at a temperature about or higher than the eutectic temperature of Ag and the matrix metal of the base portion.
2. A heat-treated contact as claimed in claim 1, in which the base portion is made from copper, and the contact is subjected to a temperature higher than 779°C for a period of less than 10 seconds.
3. The method of manufacturing a composite electrical contact, comprising clading an internally oxidized contact member, made from an alloy of 1.5-10% by weight tin, 0.5-6.0% by weight indium, a trace amount of an iron family element metal and the balance silver, to a base member made from copper or copper-matrix alloys, and subjecting the composite contact to a temperature approximately equal to or higher than the eutectic temperature of Ag and the matrix metal of said base member, and for an interval sufficient to cause the metal of said base member to diffuse into the matrix of said contact member.
CA288,044A 1977-06-16 1977-10-04 Silver-tin oxide composite electrical contact Expired CA1087235A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US80704677A 1977-06-16 1977-06-16
US807,046 1977-06-16

Publications (1)

Publication Number Publication Date
CA1087235A true CA1087235A (en) 1980-10-07

Family

ID=25195434

Family Applications (1)

Application Number Title Priority Date Filing Date
CA288,044A Expired CA1087235A (en) 1977-06-16 1977-10-04 Silver-tin oxide composite electrical contact

Country Status (9)

Country Link
JP (1) JPS607328B2 (en)
AU (1) AU511436B2 (en)
BR (1) BR7801633A (en)
CA (1) CA1087235A (en)
DE (1) DE2747087C2 (en)
FR (1) FR2394880A1 (en)
GB (1) GB1604976A (en)
HK (1) HK28082A (en)
MX (1) MX145764A (en)

Families Citing this family (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5512773Y2 (en) * 1974-03-15 1980-03-21
JPS62268015A (en) * 1986-05-15 1987-11-20 株式会社 徳力本店 Composite contact material and manufacture thereof
JPS62268019A (en) * 1986-05-15 1987-11-20 株式会社 徳力本店 Composite contact material
JPH0799655B2 (en) * 1987-01-07 1995-10-25 株式会社東富士製作所 Composite electrical contact
JPH0337593Y2 (en) * 1987-07-08 1991-08-08
DE3813142A1 (en) * 1988-04-20 1989-11-09 Duerrwaechter E Dr Doduco Strip-shaped or sheet-shaped semi-finished product for electrical contacts
JP2662895B2 (en) * 1988-10-03 1997-10-15 富士電機株式会社 Electrical contacts with base metal
JPH04311543A (en) * 1991-04-09 1992-11-04 Chugai Electric Ind Co Ltd Ag-sno-ino electrical contact material and production thereof
FI119647B (en) * 2005-04-29 2009-01-30 Outotec Oyj A method for forming a dense silver surface on an aluminum piece

Family Cites Families (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3151385A (en) * 1962-10-03 1964-10-06 Gibson Electric Company Method of forming electrical contacts
US3874941A (en) * 1973-03-22 1975-04-01 Chugai Electric Ind Co Ltd Silver-metal oxide contact materials
FR2236261A1 (en) * 1973-07-05 1975-01-31 Sumitomo Electric Industries Electrical contacts of silver- indium- and tin- oxides - made by internal oxidn. of silver-indium-tin alloys, and with excellent properties
JPS5324010B2 (en) * 1973-12-06 1978-07-18
JPS5526697B2 (en) * 1973-07-05 1980-07-15
US3933485A (en) * 1973-07-20 1976-01-20 Chugai Denki Kogyo Kabushiki-Kaisha Electrical contact material
DE2441327A1 (en) * 1974-08-29 1976-03-11 Transformatoren Union Ag Tap changer contact path soldering - uses MF induction heater with special inductor for soldering heat supply
JPS5647255B2 (en) * 1974-10-08 1981-11-09
JPS51121798A (en) * 1975-04-18 1976-10-25 Hitachi Ltd Thick film resistor
JPS523193A (en) * 1975-06-24 1977-01-11 Sumitomo Electric Ind Ltd Electric contact material
JPS6013720B2 (en) * 1977-07-11 1985-04-09 株式会社東芝 Leg height adjustment device

Also Published As

Publication number Publication date
DE2747087C2 (en) 1985-12-19
AU511436B2 (en) 1980-08-21
MX145764A (en) 1982-03-29
DE2747087A1 (en) 1978-12-21
BR7801633A (en) 1979-01-16
JPS607328B2 (en) 1985-02-23
AU2969477A (en) 1979-04-26
GB1604976A (en) 1981-12-16
FR2394880A1 (en) 1979-01-12
FR2394880B1 (en) 1982-04-30
JPS547157A (en) 1979-01-19
HK28082A (en) 1982-07-02

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