Patent US3964943A successfully refreshed from Google Patents.
US3964943A
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US
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Method of producing electrical resistor
Assignee: Danfoss AS
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Filing: 1974-11-29
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Granted: 1976-06-22
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Expires: 1994-11-29
Abstract
Abstract The invention relates to an electrical resistor with a SiC body, particularly for ignition or heating purposes, and to a method of producing such electrical resistor.
Inventors
- 👤 Niels Lervad Andersen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 13:59
CPC Classifications
F; F23; F23Q; F23Q7/00; F23Q7/22; H; H01; H01C; H01C7/00; H01C7/04; H01C7/042; H01C7/048; H05; H05B; H05B3/00; H05B3/62; H05B3/64; Y; Y10; Y10T; Y10T29/00; Y10T29/49; Y10T29/49002; Y10T29/49082
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
76 words
A method of producing a silicon carbide electrical resistor which comprises forming under pressure a dense and substantially nonporous body consisting essentially of silicon carbide and free silicon, and etching a middle portion of said body with acid to remove essentially all the free silicon therefrom to thereby obtain a middle portion consisting essentially of a porous matrix of silicon carbide free of silicon and two end portions consisting essentially of silicon carbide and free silicon.
Claim 2
Independent Claim
76 words
A method of producing a silicon carbide electrical resistor which comprises forming under pressure a dense and substantially nonporous body consisting essentially of silicon carbide and free silicon, and etching a middle portion of said body with acid to remove essentially all the free silicon therefrom to thereby obtain a middle portion consisting essentially of a porous matrix of silicon carbide free of silicon and two end portions consisting essentially of silicon carbide and free silicon.
Claim 3
Dependent Claim
26 words
A method according to claim 1 wherein a metal is applied to said end portions which forms a eutectic with free silicon in said end portions.
Claim 4
Dependent Claim
65 words
A method according to claim 2 wherein said body consists of silicon carbide and carbon, the amount of carbon being less than stoichiometric with respect to the amount of silicon diffused into the body, and wherein the body is subsequently sintered to cause the reaction in situ of said carbon and said silicon to provide said body consisting essentially of silicon carbide and free silicon.
Claim 5
Dependent Claim
27 words
A method according to claim 3 wherein before impregnation with silicon the body is treated with SiO at least in the region of said two end portions.
Claim 6
Dependent Claim
31 words
A method according to claim 1 wherein, before etching, the cross-sectional area of middle portion of the body is reduced relative to the cross-sectional area of the end portions by grinding.
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) | 1979-06-22 | 1979-12-22 | 1980-06-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-06-22 | 1983-12-22 | 1984-06-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-06-22 | 1987-12-22 | 1988-06-22 | $7700.00 | Window Closed / Lapsed |