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US4122220A
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US
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Method for reducing the gas permeability of a sintered porous silicon nitride body
Assignee: Rosenthal AG
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Filing: 1977-09-06
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Granted: 1978-10-24
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Expires: 1997-09-06
Abstract
Abstract Silicon nitride bodies are improved by being impregnated with a silicon halide which is then converted to silicon imide in the pores of the body, which, in turn, is converted into silicon nitride.
Inventors
- 👤 Godehard Sussmuth
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 12:48
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/515; C04B35/58; C04B35/584; C04B35/591
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
70 words
A method of reducing the gas permeability of a sintered porous silicon nitride body, the method including the steps of impregnating said body with a silicon tetrahalide selected from the group consisting of silicon tetrachloride and silicon tetrabromide, precipitating silicon imide in the pores of said body by contacting the impregnated body with ammonia, and converting the silicon imide into silicon nitride by firing the body in a nitrogen atmosphere.
Claim 2
Independent Claim
70 words
A method of reducing the gas permeability of a sintered porous silicon nitride body, the method including the steps of impregnating said body with a silicon tetrahalide selected from the group consisting of silicon tetrachloride and silicon tetrabromide, precipitating silicon imide in the pores of said body by contacting the impregnated body with ammonia, and converting the silicon imide into silicon nitride by firing the body in a nitrogen atmosphere.
Claim 3
Dependent Claim
18 words
A method according to claim 1, in which the impregnation with a silicon tetrahalide is effected under pressure.
Claim 4
Dependent Claim
25 words
A method according to claim 1, in which the impregnating and the precipitating steps are repeated at least once before firing in a nitrogen atmosphere.
Claim 5
Dependent Claim
31 words
A method according to claim 1, in which prior to firing, the body is subjected to a temperature below the firing temperature to remove any ammonium halide formed during the precipitation.
Claim 6
Dependent Claim
21 words
A method according to claim 1, in which the silicon tetrahalide is maintained out of contact with both oxygen and water.
Claim 7
Dependent Claim
41 words
A method according to claim 1, in which the method is effected in a nitrogen atmosphere, the impregnation and precipitation is repeated at least once prior to firing, and in which the firing is effected at a temperature above 1500° C.
Claim 8
Dependent Claim
42 words
A method according to claim 6, in which at least one impregnation is effected under pressure, and in which, prior to firing, the body is subjected to a temperature below the firing temperature to remove any ammonium halide formed during the precipitation.
Claim 9
Dependent Claim
15 words
A method according to claim 7, in which the silicon tetrahalide is SiCl 4 .
References Cited (Backward Citations)
CA537716A
Cited
GB1432559A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1981-10-23 | 1982-04-24 | 1982-10-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-10-23 | 1986-04-24 | 1986-10-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-10-23 | 1990-04-24 | 1990-10-24 | $7700.00 | Window Closed / Lapsed |