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Patent US3974106A successfully refreshed from Google Patents.
US3974106A
Expired / Lapsed
US
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Ceramic electrical resistance igniter
Assignee: Saint Gobain Abrasives Inc
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Filing: 1974-05-22
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Granted: 1976-08-10
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Expires: 1994-05-22
Abstract
Abstract A ceramic resistance gas igniter comprised of 10 to 60% by weight of silicon carbide and 40 to 90% by weight of silicon nitride, slicon oxynitride, or silicon aluminum oxynitride, and having a density preferably greater than 95% of the theoretical density of the composite. As a result of the combination of high density and composition, the igniters have moduli of rupture in excess of 80,000 p.s.i., a resistivity range of from 0.1 to 10 4 ohm centimeters, and superior resistance to corrosive gases.
Inventors
- 👤 David W. Richerson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 15:21
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/515; C04B35/58; C04B35/584; C04B35/593; C04B35/597; F; F23; F23Q; F23Q7/00; F23Q7/22; H; H05; H05B; H05B3/00; H05B3/10; H05B3/12; H05B3/14; H05B3/148
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
213 words
A ceramic resistance igniter comprising a sintered mixture of from 10 to 60% by weight of silicon carbide having an average grain size of 10 microns or less, and 40 to 90% by weight of a material selected from the group consisting of silicon nitride, silicon aluminum oxynitride, silicon oxynitride and mixtures thereof, material having an average grain size of 10 microns or less; and sintered mixture having a density of at least 90% of its theoretical density, a room temperature resistivity of from 0.1 to 10 4 ohm centimeters, a modulus of rupture in excess of 80,000 p.s.i. measured at room temperature and under 3 point loading, and having a resistance differential between the terminal connecting ends of said igniter and the intermediate zone thereof; the resistance of said terminal ends being less than 75% of that of said intermediate zone, and having a composition of from 12 to 60% by weight of silicon carbide and 38 to 88% by weight of a material selected from the group consisting of silicon nitride, silicon oxynitride, silicon aluminum oxynitride, and mixtures thereof, said silicon carbide content being at least 2% by weight higher than that of the intermediate zone; said igniter being capable of attaining a temperature of at least 1000°C within 3 minutes.
Claim 2
Dependent Claim
213 words
A ceramic resistance igniter comprising a sintered mixture of from 10 to 60% by weight of silicon carbide having an average grain size of 10 microns or less, and 40 to 90% by weight of a material selected from the group consisting of silicon nitride, silicon aluminum oxynitride, silicon oxynitride and mixtures thereof, material having an average grain size of 10 microns or less; and sintered mixture having a density of at least 90% of its theoretical density, a room temperature resistivity of from 0.1 to 10 4 ohm centimeters, a modulus of rupture in excess of 80,000 p.s.i. measured at room temperature and under 3 point loading, and having a resistance differential between the terminal connecting ends of said igniter and the intermediate zone thereof; the resistance of said terminal ends being less than 75% of that of said intermediate zone, and having a composition of from 12 to 60% by weight of silicon carbide and 38 to 88% by weight of a material selected from the group consisting of silicon nitride, silicon oxynitride, silicon aluminum oxynitride, and mixtures thereof, said silicon carbide content being at least 2% by weight higher than that of the intermediate zone; said igniter being capable of attaining a temperature of at least 1000°C within 3 minutes.
Claim 3
Dependent Claim
148 words
A ceramic resistance igniter comprising a sintered mixture of from 20 to 40% by weight of silicon carbide and 60 to 80% by weight of a material selected from the group consisting of silicon nitride, silicon oxynitride, silicon aluminum oxynitride, and mixtures thereof, said sintered mixture having a density of at least 95% of its theoretical density, a room temperature resistivity of from 2 to 200 ohm centimeters, a 3 point load room temperature modulus of rupture of at least 100,000 p.s.i., said sintered silicon carbide having an average grain size of 10 microns or less, and said igniter having a resistance differential between its terminal connecting ends and the intermediate zone thereof, the resistance of said terminal connecting ends being at least 25% lower than the resistance of said intermediate zone, said intermediate zone being capable of attaining a temperature of at least 1000°C within 60 seconds.
Claim 4
Dependent Claim
148 words
A ceramic resistance igniter comprising a sintered mixture of from 20 to 40% by weight of silicon carbide and 60 to 80% by weight of a material selected from the group consisting of silicon nitride, silicon oxynitride, silicon aluminum oxynitride, and mixtures thereof, said sintered mixture having a density of at least 95% of its theoretical density, a room temperature resistivity of from 2 to 200 ohm centimeters, a 3 point load room temperature modulus of rupture of at least 100,000 p.s.i., said sintered silicon carbide having an average grain size of 10 microns or less, and said igniter having a resistance differential between its terminal connecting ends and the intermediate zone thereof, the resistance of said terminal connecting ends being at least 25% lower than the resistance of said intermediate zone, said intermediate zone being capable of attaining a temperature of at least 1000°C within 60 seconds.
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) | 1979-08-10 | 1980-02-09 | 1980-08-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-08-10 | 1984-02-09 | 1984-08-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-08-10 | 1988-02-09 | 1988-08-10 | $7700.00 | Window Closed / Lapsed |