US4280989A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of preparing silicon nitride
Assignee: Toshiba Corp
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Filing: 1980-06-12
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Granted: 1981-07-28
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Expires: 2000-06-12
Abstract
Abstract A method of producing silicon nitride which comprises heating silica in a gas atmosphere comprising hydrocarbon gas, ammonia gas and hydrogen gas.
Inventors
- 👤 Motoo Seimiya
- 👤 Katsutoshi Nishida
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 22:25
CPC Classifications
C; C01; C01B; C01B21/00; C01B21/06; C01B21/068; C01B21/0685; B; B82; B82Y; B82Y30/00; C01P; C01P2004/00; C01P2004/60; C01P2004/62; C01P2004/64
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
67 words
A method of producing silicon nitride powder which comprises heating finely divided particulate silica to a temperature of 1200° C. to 1600° C. in a gas atmosphere comprising hydrocarbon gas, ammonia gas and hydrogen gas wherein the volume ratio of ammonia (NH 3 )/hydrocarbon (methane equivalent) is between 0.1 and 50 and the volume ratio of hydrogen (H 2 )/hydrocarbon (methane equivalent) is between 1 and 100.
Claim 2
Independent Claim
67 words
A method of producing silicon nitride powder which comprises heating finely divided particulate silica to a temperature of 1200° C. to 1600° C. in a gas atmosphere comprising hydrocarbon gas, ammonia gas and hydrogen gas wherein the volume ratio of ammonia (NH 3 )/hydrocarbon (methane equivalent) is between 0.1 and 50 and the volume ratio of hydrogen (H 2 )/hydrocarbon (methane equivalent) is between 1 and 100.
Claim 3
Dependent Claim
19 words
The method of claim 1, wherein the silica is heated to a temperature of 1350° C. to 1500° C.
Claim 4
Dependent Claim
14 words
The method of claim 1, wherein said hydrocarbon gas is a lower paraffinic hydrocarbon.
Claim 5
Dependent Claim
21 words
The method of claim 1, wherein the volume ratio of ammonia (NH 3 )/hydrocarbon (methane equivalent) is between 1 and 10.
Claim 6
Dependent Claim
23 words
The method of claim 1, or 4, wherein the volume ratio of hydrogen (H 2 )/hydrocarbon (methane equivalent) is between 5 and 50.
Claim 7
Dependent Claim
18 words
The method of claim 1, wherein the mean particle size of said silica is below about 0.1 micron.
Claim 8
Dependent Claim
19 words
The method of claim 1, wherein the mean particle size of said silica is between 0.01 and 0.05 micron.
Claim 9
Dependent Claim
16 words
The method of claim 1, wherein the silicon nitride produced is α-Si 3 N 4 .
Claim 10
Dependent Claim
29 words
The method of claim 1, wherein the silicon nitride powder produced is heated in an oxidizing atmosphere to remove carbon adhered to the surface of said silicon nitride powder.
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) | 1984-07-27 | 1985-01-26 | 1985-07-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-07-27 | 1989-01-26 | 1989-07-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-07-27 | 1993-01-26 | 1993-07-28 | $7700.00 | Window Closed / Lapsed |