US3778576A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Tungsten electrical switching contacts
Assignee: ECHLIN MANUF CORP
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Filing: 1971-10-07
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Granted: 1973-12-11
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Expires: 1991-10-07
Abstract
Abstract A tungsten contact disc is treated by burnishing so as to smooth and compact the contact surface and remove the surface-crazed metals and oxides, while simultaneously filling the surface pores with a contaminant such as iron. The contaminants present in the pores are subsequently removed by immersing the contact disc in a dissolving agent, and the remaining natural oxides of the tungsten are removed from the walls of the pores by cathodic reduction, so as to create large pore sites which are free of oxides and contaminants. Next, there is applied a coating of a diffusion-absorbing metal, such as nickel, to the contact disc to provide a diffusion-absorbing layer for an outer film of gold. The gold lining the pore sites is applied with a thickness sufficient to maintain an amount of non-alloyed gold on the contact surface after some of the gold has been diffusion absorbed by the underlying nickel layer. During electrical switching operations, the gold alloys with the nickel, and the gold and gold alloy lining the pore surfaces are effective to prevent oxide formation on the pore surfaces and to substantially reduce surface destruction by the arc heat, thereby affording a longer contact operating life.
Inventors
- 👤 H Anderson
- 👤 H Gackstetter
- 👤 G Shove
- 👤 L Morin
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 17:24
CPC Classifications
H; H01; H01H; H01H1/00; H01H1/02; H01H1/021
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
26 words
A contact disc as recited in claim 1, wherein said refractory metal is tungsten, said good conducting metal is gold and said diffusion-absorbing metal is nickel.
Claim 2
Dependent Claim
142 words
A contact disc for switching electrical current comprising: a. a porous body of a refractory metal, selected from the group consisting of tungsten, molybdenum, rhenium and niobium; b. said porous body having pore sites open at the contact surface; c. a thin film of a good conducting metal selected from the group consisting of gold, silver, platinum, palladium and rhodium, covering said contact surface and the walls of said pore sites; and d. an intermediate layer of a diffusion-absorbing metal, selected from the group consisting of nickel and cobalt, positioned between said conducting metal film, and said contact surface and the walls of said pore sites, said intermediate layer adhering to the refractory metal and providing a diffusion-absorbing layer for said conducting metal film, and said intermediate layer of a diffusion-absorbing metal having a thickness of about 50 X 10 6 inches.
Claim 3
Dependent Claim
24 words
A contact disc as recited in claim 3, wherein said good conducting metal film has a thickness of about 50 X 10 6 INCHES.
Claim 4
Dependent Claim
155 words
A contact disc for switching electrical current in an automobile ignition contact switching circuit, comprising: a. a porous body of refractory metal, selected from the group consisting of tungsten, molybdenum, rhenium and niobium, said porous body having pore sites open at the contact surface; b. a thin coating of a diffusion-absorbing metal, selected from the group consisting of nickel and cobalt, coating the contact surface and the walls of said pore sites; c. an outer film of a good conducting metal, selected from the group consisting of gold, silver, platinum, palladium and rhodium, on top of said diffusion-absorbing metal, said good conducting metal film having a thickness of about 50 X 10 6 inches; and d. said diffusion-absorbing metal being bonded to said refractory metal and said good conductor metal being alloyed and adhered to said diffusion-absorbing metal as a result of subjecting the contact disc to the electrical switching current across the contact surface.
Claim 5
Dependent Claim
75 words
A contact disc as recited in claim 5, wherein said diffusion-absorbing metal and said good conductor metal are substantially not present on the contact surface in those areas where raised projections are located, while said metals remain as a lining on the walls of said pore sites, as a result of said metals being boiled off and evaporated from said raised projections on said contact surface by the arc heat of the electrical switching current.
Claim 6
Dependent Claim
137 words
A contact disc for switching electrical current, comprising: a. a porous body of a refractory metal, selected from the group consisting of tungsten, molybdenum, rhenium and niobium, said porous body having pore sites which are open at a contact surface thereof; b. a thin film of a good conducting metal, selected from the group consisting of gold, silver, platinum, palladium and rhodium, covering said contact surface and lining the pore sites, and said good conducting metal film having a thickness of about 50 X 10 6 inches; and c. a coating of diffusion-absorbing metal between said contact surface and said film of good conducting metal, said difFusion-absorbing metal adhering to said refractory metal and providing a diffusion-absorbing layer for said good conducting metal, and said diffusion-absorbing metal having a thickness of about 50 X 10 6 inches.
Claim 7
Dependent Claim
26 words
A contact disc as recited in claim 7, wherein the walls of said pore sites at the contact surface are substantially free from contaminants and oxides.
Claim 8
Dependent Claim
47 words
A contact disc as recited in claim 7, wherein said good conductor metal film has a thickness sufficient to maintain an amount of non-alloyed good conductor metal on the contact surface after someofsaid good conductor metal has been diffusion-absorbed by the underlying layer of said diffusion-absorbing metal.
Claim 9
Dependent Claim
23 words
A contact disc as recited in claim 7, wherein said porous body of refractory metal has a generally smooth and compacted contact surface.
Claim 10
Dependent Claim
29 words
A contact disc as recited in claim 10, wherein said contact disc surface is provided with said smooth and compacted surface characteristics by burnishing said contact disc during manufacture.
Claim 11
Dependent Claim
40 words
A contact disc as recited in claim 7, wherein said diffusion-absorbing metal and said film of good conducting metal line the walls of said pore sites, while said metals substantially do not line the raised projections at the contact surface.
Claim 12
Dependent Claim
65 words
A contact disc as recited in claim 7, wherein said diffusion-absorbing metal is bonded to said refractory metal and said good conductor metal is alloyed and adhered to said diffusion-absorbing metal at those locations where said pore sites are lined with said diffusion-absorbing metal and said good conducting metal, by means of subjecting said contact disc to an electrical switching current across the contact surface.
Claim 13
Dependent Claim
171 words
A contact disc for switching electrical current, comprising: a. a porous body of refractory metal, selected from the group consisting of tungsten, molybdenum, rhenium and niobium, said porous body having a smooth and compacted contact surface which is provided by burnishing said porous body in the presence of a contaminant material while filling the pore sites located at the contact surface with said contaminant material, and thereafter dissolving said contaminants and remaining oxides to provide pore sites which are open at the contact surface and substantially free of oxides and contaminants; b. a thin film of diffusion-absorbing metal, selected from the group consisting of nickel and cobalt, coating the walls of said pore sites, said diffusion-absorbing metal film having a thickness of about 50 X 10 6 inches; and c. an outer film of a good conducting metal, selected from the group consisting of gold, silver, platinum, palladium and rhodium, on top of said diffusion-absorbing metal, said good conducting metal film having a thickness of about 50 X 10 6 inches.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-12-10 | 1977-06-11 | 1977-12-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-12-10 | 1981-06-11 | 1981-12-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-12-10 | 1985-06-11 | 1985-12-11 | $7700.00 | Window Closed / Lapsed |