US5032554A
Expired / Lapsed
US
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Sintered silicon nitride products
Assignee: Niterra Co Ltd
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Filing: 1989-12-14
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Granted: 1991-07-16
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Expires: 2009-12-14
Abstract
Abstract A sintered silicon nitride product comprises from 72 to 98% by weight of silicon nitride, from 1 to 8% by weight of vanadium pentoxide, and from 1 to 20% by weight of one or more oxides of rare earth elements. The vanadium pentoxide and the oxide of rare earth elements accelerate the densification of the sintered product, and provide high strength at high temperature as well as excellent oxidation resistance to the sintered product.
Inventors
- 👤 Kenichi Mizuno
- 👤 Yo Tajima
- 👤 Masakazu Watanabe
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 13:17
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/515; C04B35/58; C04B35/584; C04B35/593; C04B35/5935
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
46 words
A sintered silicon nitride product consisting essentially of: from 72% to 98% by weight of silicon nitride; from 1% to 8% by weight of vanadium compound calculated as vanadium pentoxide; and from 1% to 20% by weight of at least one oxide of rare earth elements.
Claim 2
Dependent Claim
46 words
A sintered silicon nitride product consisting essentially of: from 72% to 98% by weight of silicon nitride; from 1% to 8% by weight of vanadium compound calculated as vanadium pentoxide; and from 1% to 20% by weight of at least one oxide of rare earth elements.
Claim 3
Dependent Claim
46 words
The sintered silicon nitride product of claim 1, wherein the at least one oxide of rare earth elements is chosen from the group consisting of Y 2 O 3 , Er 2 O 3 , Yb 2 O 3 , and Sc 2 O 3 .
Claim 4
Dependent Claim
28 words
The sintered silicon nitride product of claim 2, wherein the oxide of rare earth elements is Y 2 O 3 having an average particle size of 2 microns.
Claim 5
Dependent Claim
21 words
The sintered silicon nitride product of claim 1, wherein the at least one oxide of rare earth elements is 99.9% pure.
Claim 6
Dependent Claim
29 words
The sintered silicon nitride product of claim 1, wherein the silicon nitride is Si 3 N 4 powder in the alpha-phase having an average particle size of 0.7 microns.
Claim 7
Dependent Claim
20 words
The sintered silicon nitride product of claim 5, wherein the vanadium pentoxide has an average particle size of 1 micron.
Claim 8
Dependent Claim
50 words
The sintered silicon nitride product of claim 1, wherein the sintered silicon nitride product is sintered in a two-step gas-pressure sintering process comprising a first sintering in a nitrogen gas atmosphere under pressure, followed by resintering of the sintered product obtained in a nitrogen gas atmosphere under a higher pressure.
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) | 1994-07-15 | 1995-01-14 | 1995-07-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-07-15 | 1999-01-14 | 1999-07-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-07-15 | 2003-01-14 | 2003-07-16 | $7700.00 | Window Closed / Lapsed |