US4540674A
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Silicon nitride composite refractories
Assignee: Krosaki Harima Corp
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Filing: 1983-08-11
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Granted: 1985-09-10
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Expires: 2003-08-11
Abstract
Abstract The present invention relates to silicon nitride composite refractories having silicon nitride bonds therein and having an increased thermal shock-resistance, an improved molten steel-resistance and an improved mechanical strength, which consists of silicon nitride at 20 to 60 wt %, refractory materials at 10 to 50 wt % and boron nitirde at 1 to 30 wt %, or additionally carbon fibers of 0.5 to 10 wt %. The above described characteristics can be realized because the silicon nitride bonds are bonding structures.
Inventors
- 👤 Akira Watanabe
- 👤 Yoshimitsu Takeuchi
- 👤 Noboru Shinoda
- 👤 Tetsusaburo Isono
- 👤 Kenji Fujiwara
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 21:06
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/515; C04B35/58; C04B35/584; C04B35/591; C04B35/71; C04B35/78; C04B35/80
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
71 words
Silicon nitride composite refractories consisting of: 20 to 60 wt% silicon nitride; 10to 50 wt% refractory materials in powder form selected from the group consisting of magnesia, spinel, alumina, zirconia and carbides, said refractory materials having grain sizes of 50 microns or more, and 1 to 30 wt% boron nitride, said composite refractories containing silicon nitride bonds formed by the reaction sintering of silicon, said silicon nitride bonds being bonded structures.
Claim 2
Dependent Claim
71 words
Silicon nitride composite refractories consisting of: 20 to 60 wt% silicon nitride; 10to 50 wt% refractory materials in powder form selected from the group consisting of magnesia, spinel, alumina, zirconia and carbides, said refractory materials having grain sizes of 50 microns or more, and 1 to 30 wt% boron nitride, said composite refractories containing silicon nitride bonds formed by the reaction sintering of silicon, said silicon nitride bonds being bonded structures.
Claim 3
Dependent Claim
92 words
Silicon nitride composite refractories consisting of: 20 to 60 wt% silicon nitride; 10 to 50 wt% refractory materials in powder form selected from the group consisting of magnesia, spinel, alumina, zirconia and carbides, said refractory materials having grain sizes of 50 microns or more, and 1 to 30 wt% of boron nitride, carbonaceous materials or both, said carbonaceous materials being selected from the group consisting of graphite, coke and carbon black, said composite refractories containing silicon nitride bonds formed by the reaction sintering of silicon, said silicon nitride bonds being bonded structures.
Claim 4
Dependent Claim
92 words
Silicon nitride composite refractories consisting of: 20 to 60 wt% silicon nitride; 10 to 50 wt% refractory materials in powder form selected from the group consisting of magnesia, spinel, alumina, zirconia and carbides, said refractory materials having grain sizes of 50 microns or more, and 1 to 30 wt% of boron nitride, carbonaceous materials or both, said carbonaceous materials being selected from the group consisting of graphite, coke and carbon black, said composite refractories containing silicon nitride bonds formed by the reaction sintering of silicon, said silicon nitride bonds being bonded structures.
Claim 5
Dependent Claim
23 words
Silicon nitride composite refractories as set forth in claim 2 wherein said carbonaceous materials have a grain size of 1 mm or less.
Claim 6
Dependent Claim
30 words
Silicon nitride composite refractories as set forth in claim 2 which carbonaceous materials contain carbon fibers in an amount of up to 10% by weight based on the composite refractories.
Claim 7
Dependent Claim
22 words
Silicon nitride composite refractories as set forth in claim 4 wherein said carbon fibers are present at 0.5 to 10% by weight.
Claim 8
Dependent Claim
25 words
Silicon nitride composite refractories as set forth in claim 1 wherein said carbides are selected from the group consisting of SiC and B 4 C.
Claim 9
Dependent Claim
21 words
Silicon nitride composite refractories of claims 1 and 2 wherein the reaction and sintering is performed at 1,300° to 1,500° C.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1988-09-09 | 1989-03-11 | 1989-09-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-09-09 | 1993-03-11 | 1993-09-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-09-09 | 1997-03-11 | 1997-09-10 | $7700.00 | Window Closed / Lapsed |