US4521393A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of manufacturing β type silicon nitride whiskers
Assignee: Coorstek KK
•
Filing: 1984-06-26
•
Granted: 1985-06-04
•
Expires: 2004-06-26
Abstract
Abstract Silicon nitride whiskers having a long fiber length in which β type silicon nitride is well developed are produced by reacting a mixture of silica, carbon and cryolite in the specific molar ratio in a mixed gas atmosphere of N 2 and NH 3 by heating the mixture at a temperature of 1,250°-1,450° C. Kira of a ceramic industry waste may be used in place of silica and in this case N 2 alone is used as a nitriding atmosphere.
Inventors
- 👤 Hajime Saito
- 👤 Tetsuro Urakawa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 18:50
CPC Classifications
C; C30; C30B; C30B25/00; C30B25/005; C30B29/00; C30B29/10; C30B29/38
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
103 words
A method of manufacturing β type silicon nitride whiskers, which comprises preparing a mixture of silica, carbon, and cryolite in a molar ratio of 1:(2˜10):(1/12˜1/4), reacting said mixture in a mixed gas atmosphere of N 2 and NH 3 obtained by adding NH 3 to N 2 , in a molar ratio of not higher than 1/5 based on N 2 by heating the mixture at a temperature of 1,250°-1,450° C., said NH 3 being present in an amount sufficient to effect a higher content of β type silicon nitride than that produced by said method in the absence of NH 3 .
Claim 2
Independent Claim
103 words
A method of manufacturing β type silicon nitride whiskers, which comprises preparing a mixture of silica, carbon, and cryolite in a molar ratio of 1:(2˜10):(1/12˜1/4), reacting said mixture in a mixed gas atmosphere of N 2 and NH 3 obtained by adding NH 3 to N 2 , in a molar ratio of not higher than 1/5 based on N 2 by heating the mixture at a temperature of 1,250°-1,450° C., said NH 3 being present in an amount sufficient to effect a higher content of β type silicon nitride than that produced by said method in the absence of NH 3 .
Claim 3
Dependent Claim
20 words
The method according to claim 1, wherein the molar ratio of silica to carbon (SiO 2 :C) is about 1:4.
Claim 4
Dependent Claim
23 words
The method according to claim 1, wherein the molar ratio of silica to cryolite (SiO 2 :Na 3 AlF 6 ) is 1:1/10˜1/6.
Claim 5
Dependent Claim
21 words
The method according to claim 1, wherein the molar ratio of NH 3 to N 2 is not higher than 1/12.
Claim 6
Dependent Claim
13 words
The method according to claim 1, wherein the reaction temperature is 1,300°-1,400° C.
Claim 7
Independent Claim
60 words
A method of manufacturing β type silicon nitride whiskers by using Kira as a silica source, which comprises preparing a mixture of Kira, carbon and cryolite in a molar ratio of silica contained in Kira, carbon, and cryolite of 1:(3˜13):(1/12˜1), reacting the mixture in an atmosphere of N 2 gas by heating the mixture at a temperature of 1,250°-1,450° C.
Claim 8
Independent Claim
60 words
A method of manufacturing β type silicon nitride whiskers by using Kira as a silica source, which comprises preparing a mixture of Kira, carbon and cryolite in a molar ratio of silica contained in Kira, carbon, and cryolite of 1:(3˜13):(1/12˜1), reacting the mixture in an atmosphere of N 2 gas by heating the mixture at a temperature of 1,250°-1,450° C.
Claim 9
Dependent Claim
17 words
The method according to claim 6, wherein the molar ratio of silica to carbon is approximately 1:8.
Claim 10
Dependent Claim
17 words
The method according to claim 6, wherein the molar ratio of silica to cryolite is approximately 1:1/3.
Claim 11
Dependent Claim
14 words
The method according to claim 6, wherein the reaction temperature is approximately 1,350° C.
References Cited (Backward Citations)
US3394991A
Cited
US3244480A
Cited
US3413090A
Cited
JPS4927755A
Cited
JPS4945000A
Cited
JPS5112320A
Cited
US4122152A
Cited
US4428916A
Cited
JPS5425299A
Cited
JPS5717499A
Cited
EP0080050A1
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-06-03 | 1988-12-03 | 1989-06-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-06-03 | 1992-12-03 | 1993-06-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-06-03 | 1996-12-03 | 1997-06-04 | $7700.00 | Window Closed / Lapsed |