US4483839A
Expired / Lapsed
US
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Process for producing silicon nitride
Assignee: Toyota Central R&D Labs Inc
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Filing: 1983-07-18
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Granted: 1984-11-20
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Expires: 2003-07-18
Abstract
Abstract Impurities are removed from chaff by acid treatment, and the chaff is heated for carbonization. Silicon is reduced from the carbonized chaff, and nitrided to form silicon nitride.
Inventors
- 👤 Masahiro Sugiura
- 👤 Toshio Kandori
- 👤 Haruo Doi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 14:30
CPC Classifications
C; C01; C01B; C01B21/00; C01B21/06; C01B21/068; C01B21/0685; C01P; C01P2002/00; C01P2002/70; C01P2002/72
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
50 words
A process for producing silicon nitride, comprising: immersing chaff in a solution of an acid for a time sufficient to remove impurity elements therefrom; washing said chaff with water; drying said chaff; heating said chaff to carbonize it; and reducing silicon from said carbonized chaff and simultaneously nitriding said silicon.
Claim 2
Dependent Claim
50 words
A process for producing silicon nitride, comprising: immersing chaff in a solution of an acid for a time sufficient to remove impurity elements therefrom; washing said chaff with water; drying said chaff; heating said chaff to carbonize it; and reducing silicon from said carbonized chaff and simultaneously nitriding said silicon.
Claim 3
Dependent Claim
17 words
A process according to claim 1, wherein said solution has an acid concentration of 0.01 to 10N.
Claim 4
Dependent Claim
19 words
A process according to claim 2, wherein said chaff is left in said solution for one to 20 hours.
Claim 5
Dependent Claim
28 words
A process according to claim 2, wherein said acid is an inorganic acid selected from the group consisting of hydrochloric acid, nitric acid, sulfuric acid and phosphoric acid.
Claim 6
Dependent Claim
26 words
A process according to claim 2, wherein said acid is an organic acid selected from the group consisting of formic acid, acetic acid and tartaric acid.
Claim 7
Dependent Claim
15 words
A process according to claim 1, wherein said heating is carried out before said immersing.
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) | 1987-11-20 | 1988-05-21 | 1988-11-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-11-20 | 1992-05-21 | 1992-11-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-11-20 | 1996-05-21 | 1996-11-20 | $7700.00 | Window Closed / Lapsed |