US4517168A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Grinding amorphous silicon nitride powder prior to heating to produce crystalline silicon nitride powder
Assignee: Ube Corp
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Filing: 1983-07-26
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Granted: 1985-05-14
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Expires: 2003-07-26
Abstract
Abstract Crystalline silicon nitride powder in the form of granular particles having a large tap density and having good filling characteristics is produced by heating amorphous silicon nitride powder under an inert or reducing gas atmosphere. The amorphous silicon nitride powder is ground prior to the heating and the powder to be heated is maintained at a temperature of 1250 DEG C. to 1430 DEG C. for at least one hour in the course of temperature rise.
Inventors
- 👤 Takashi Kawahito
- 👤 Yoshinori Himukashi
- 👤 Tetsuo Yamada
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 00:03
CPC Classifications
C; C01; C01B; C01B21/00; C01B21/06; C01B21/068; C01B21/0687; C01P; C01P2002/00; C01P2002/02; C01P2004/00; C01P2004/01; C01P2004/03; C01P2004/30; C01P2004/32; C01P2004/50; C01P2004/60; C01P2004/61; C01P2006/00; C01P2006/10; C01P2006/12
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
60 words
A process for producing equiaxed crystalline silicon nitride powder having an average diameter of not more than 1.5 microns by heating amorphous silicon nitride powder under an inert or reducing gas atmosphere, wherein said amorphous silicon nitride powder is ground prior to heating and subsequently maintained at a temperature of 1250° C. to 1430° C. for at least one hour.
Claim 2
Dependent Claim
60 words
A process for producing equiaxed crystalline silicon nitride powder having an average diameter of not more than 1.5 microns by heating amorphous silicon nitride powder under an inert or reducing gas atmosphere, wherein said amorphous silicon nitride powder is ground prior to heating and subsequently maintained at a temperature of 1250° C. to 1430° C. for at least one hour.
Claim 3
Dependent Claim
22 words
A process as claimed in claim 1, wherein the grinding is carried out in the presence of a particulate crystalline grinding auxiliary.
Claim 4
Dependent Claim
27 words
A process as claimed in claim 2, wherein the grinding auxiliary is at least one member selected from the group consisting of nitrides, carbides, borides, and oxides.
Claim 5
Dependent Claim
40 words
A process as claimed in claim 2, wherein the amount of the grinding auxiliary is 0.1 to 30 parts by weight based on 100 parts by weight of the total amount of the amorphous silicon nitride and the grinding auxiliary.
References Cited (Backward Citations)
US4208215A
Cited
US4073845A
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GB2011952A
Cited
US4196178A
Cited
US4376652A
Cited
US4405589A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-05-13 | 1988-11-12 | 1989-05-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-05-13 | 1992-11-12 | 1993-05-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-05-13 | 1996-11-12 | 1997-05-14 | $7700.00 | Window Closed / Lapsed |