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US4615990A
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Silicon nitride sintered bodies and a method for their production
Assignee: Battelle Memorial Institute Inc
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Filing: 1985-09-17
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Granted: 1986-10-07
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Expires: 2005-09-17
Abstract
Abstract Silicon nitride sintered bodies which contain no more than 15% by weight metallic non-oxide compounds as silicon nitride high temperature grain growth inhibitors and total amount of 4-25% of MgO and Al 2 O 3 as densifying aids in MgO/Al 2 O 3 weight ratio being 19 to 2.
Inventors
- 👤 Dominique Richon
- 👤 Olivier de Pous
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 09:09
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/515; C04B35/58; C04B35/584
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
78 words
Silicon nitride sintered bodies which contain metal compounds selected from SiC, TiN, WC, TiC and TiB 2 , and MgO/Al 2 O 3 , characterized in having such metal compounds in a quantity by weight not exceeding 15%, the total amounts of MgO and Al 2 O 3 in a quantity by weight of 4 to 25% relative to the total of the composition and in having the MgO/Al 2 O 3 weight ratio from 19 to 2.
Claim 2
Dependent Claim
78 words
Silicon nitride sintered bodies which contain metal compounds selected from SiC, TiN, WC, TiC and TiB 2 , and MgO/Al 2 O 3 , characterized in having such metal compounds in a quantity by weight not exceeding 15%, the total amounts of MgO and Al 2 O 3 in a quantity by weight of 4 to 25% relative to the total of the composition and in having the MgO/Al 2 O 3 weight ratio from 19 to 2.
Claim 3
Dependent Claim
50 words
Silicon nitride sintered bodies according to claim 1, wherein the amount of metal compound selected from SiC, TiN and WC is 1 to 10% by weight, the amount of MgO is 5 to 15% by weight and the amount of Al 2 O 3 is 0.5 to 6% by weight.
Claim 4
Dependent Claim
30 words
Silicon nitride sintered bodies according to claim 1, characterized in that their density exceeds 3.10 g/cm 3 and their flexural strength at 1400° C. is not less than 350 MPa.
Claim 5
Independent Claim
104 words
A method of manufacturing silicon nitride sintered bodies by the pressureless sintering of a composition in powder form, which comprises mixing a raw material powder of silicon nitride containing magnesium oxide and aluminium oxide and a metal compound selected from SiC, TiN, WC, TiC and TiB 2 , the total amounts of MgO and Al 2 O 3 being 4 to 25% by weight of the composition and the MgO/Al 2 O 3 weight ratio being from 19 to 2, forming the resulting mixture into an article and firing this article at a temperature of 1650°-1830° C. in an atmosphere composed essentially of nitrogen.
Claim 6
Independent Claim
104 words
A method of manufacturing silicon nitride sintered bodies by the pressureless sintering of a composition in powder form, which comprises mixing a raw material powder of silicon nitride containing magnesium oxide and aluminium oxide and a metal compound selected from SiC, TiN, WC, TiC and TiB 2 , the total amounts of MgO and Al 2 O 3 being 4 to 25% by weight of the composition and the MgO/Al 2 O 3 weight ratio being from 19 to 2, forming the resulting mixture into an article and firing this article at a temperature of 1650°-1830° C. in an atmosphere composed essentially of nitrogen.
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) | 1989-10-06 | 1990-04-07 | 1990-10-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-10-06 | 1994-04-07 | 1994-10-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-10-06 | 1998-04-07 | 1998-10-07 | $7700.00 | Window Closed / Lapsed |