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US4716028A
Expired / Lapsed
US
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Process for preparation of high-type silicon nitride powder
Assignee: Tosoh Corp
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Filing: 1986-02-14
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Granted: 1987-12-29
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Expires: 2006-02-14
Abstract
Abstract A high alpha -type silicon nitride powder is prepared by thermally decomposing a mixture of a crystalline silicon nitride powder having an oxygen content of at least 1.0% by weight and a nitrogen-containing silane compound.
Inventors
- 👤 Kiyoshi Kasai
- 👤 Takaaki Tsukidate
- 👤 Toshihiko Arakawa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 21:51
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/515; C04B35/58; C04B35/584; C01; C01B; C01B21/00; C01B21/06; C01B21/068; C01P; C01P2002/00; C01P2002/04; C01P2004/00; C01P2004/60; C01P2004/62; C01P2006/00; C01P2006/10
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
108 words
A process of preparing crystalline silicon nitride by the thermal decomposition of a nitrogen-containing silane compound, said process comprising the steps of: forming a powder or molded body having a powder bulk density of at least 0.1 g/cm 3 expressed in terms of silicon, from a mixture of a crystalline silicon nitride powder having an oxygen content of at least 1.0% by weight and a nitrogen-containing silane compound, and thermally decomposing said mixture while said mixture is heated at a temperature-elevating rate of at least 15° C. per minute in a temperature range of from 1,350° C. to 1,550° C., to obtain thereby an α-type silicon nitride powder.
Claim 2
Dependent Claim
108 words
A process of preparing crystalline silicon nitride by the thermal decomposition of a nitrogen-containing silane compound, said process comprising the steps of: forming a powder or molded body having a powder bulk density of at least 0.1 g/cm 3 expressed in terms of silicon, from a mixture of a crystalline silicon nitride powder having an oxygen content of at least 1.0% by weight and a nitrogen-containing silane compound, and thermally decomposing said mixture while said mixture is heated at a temperature-elevating rate of at least 15° C. per minute in a temperature range of from 1,350° C. to 1,550° C., to obtain thereby an α-type silicon nitride powder.
Claim 3
Dependent Claim
38 words
The process of preparing crystalline silicon nitride according to claim 1, wherein the oxygen content of the crystalline silicon nitride powder mixed with the nitrogen-containing silane compound is in the range of from 1.0 to 3.0% by weight.
Claim 4
Dependent Claim
44 words
The process of preparing crystalline silicon nitride according to claim 1, wherein the amount of the crystalline silicon nitride in the mixture of the crystalline silicon nitride powder and the nitrogen-containing silane compound is in the range of from 0.1 to 15% by weight.
Claim 5
Dependent Claim
37 words
The process of preparing crystalline silicon nitride according to claim 1, wherein the mixture of the crystalline silicon nitride powder and the nitrogen-containing silane compound is heated at 1,400° C. to 1,700° C. to effect thermal decomposition.
Claim 6
Dependent Claim
26 words
The process of preparing crystalline silicon nitride according to claim 1, wherein the amount of α-type silicon nitride powder obtained is at least 93% by weight.
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) | 1990-12-28 | 1991-06-29 | 1991-12-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-12-28 | 1995-06-29 | 1995-12-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-12-28 | 1999-06-29 | 1999-12-29 | $7700.00 | Window Closed / Lapsed |