US4122152A
Expired / Lapsed
US
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Process for preparing silicon nitride powder having a high α-phase content
Assignee: Coorstek KK
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Filing: 1977-01-27
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Granted: 1978-10-24
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Expires: 1997-01-27
Abstract
Abstract A process for preparing silicon nitride powder having a high α-phase content which comprises the steps of (a) providing a blended powder material composed of silica powder and amorphous carbon powder having an oil absorption of not less than 100 ml/100g, the weight ratio of the carbon powder to the silica powder being not less than 0.5, and then (b) nitriding and burning the blended powder material by heating in at a temperature of from 1300° to 1700° C while feeding a nitrogen-containing, non-oxidizing gas. The product obtained by this process is suitable as a raw material for the manufacture of high-density and high-strength sintered articles of silicon nitride.
Inventors
- 👤 Masaaki Mori
- 👤 Norihira Takai
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 01:34
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/515; C04B35/58; C04B35/584; C01; C01B; C01B21/00; C01B21/06; C01B21/068; C01B21/0685; C01P; C01P2004/00; C01P2004/01; C01P2004/03; C01P2004/10; C01P2004/60; C01P2004/61; C01P2004/62
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
87 words
A process for preparing silicon nitride powder having a high α-phase content which comprises the steps of (a) providing a blended powder material composed of silica powder and amorphous carbon powder having an oil absorption of not less than 100 ml/100g, the weight ratio of said carbon powder to said silica powder being from 1 to 3, and then (b) nitriding and burning said blended powder material by heating it at a temperature of from 1300° to 1700° C. in the presence of a nitrogen-containing, non-oxidizing gas.
Claim 2
Dependent Claim
87 words
A process for preparing silicon nitride powder having a high α-phase content which comprises the steps of (a) providing a blended powder material composed of silica powder and amorphous carbon powder having an oil absorption of not less than 100 ml/100g, the weight ratio of said carbon powder to said silica powder being from 1 to 3, and then (b) nitriding and burning said blended powder material by heating it at a temperature of from 1300° to 1700° C. in the presence of a nitrogen-containing, non-oxidizing gas.
Claim 3
Dependent Claim
23 words
A process as claimed in claim 1 wherein said silica powder is volatilized silica powder and said amorphous carbon powder is lamp black.
Claim 4
Dependent Claim
35 words
A process as claimed in claim 1 wherein said nitrogen-containing, non-oxidizing gas is a gas selected from the group consisting of nitrogen gas, ammonia gas, and gaseous mixtures of nitrogen gas and an inert gas.
Claim 5
Dependent Claim
25 words
A process as claimed in claim 1 wherein said nitriding and burning step is carried out at a temperature of from 1350° to 1700° C.
Claim 6
Dependent Claim
25 words
A process as claimed in claim 1 wherein said nitriding and burning step is carried out at a temperature of from 1300° to 1550° C.
Claim 7
Dependent Claim
41 words
A process as claimed in claim 1 wherein said silica powder is a silica power selected from the group consisting of volatilized silica powder, silica powder prepared by gas phase synthesis, silica powder prepared by chemical precipitation, and ground siliceous sand.
Claim 8
Dependent Claim
15 words
A process as claimed in claim 6 wherein said silica powder is volatilized silica powder.
Claim 9
Dependent Claim
29 words
A process as claimed in claim 1 wherein said amorphous carbon powder is a carbon black selected from the group consisting of acetylene black, channel black, and lamp black.
Claim 10
Dependent Claim
15 words
A process as claimed in claim 8 wherein said amorphous carbon powder is lamp black.
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) | 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 |