US4099979A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Si3 N4 Hot-pressed with MgO
Assignee: Westinghouse Electric Corp
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Filing: 1976-12-29
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Granted: 1978-07-11
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Expires: 1996-12-29
Abstract
Abstract This invention relates generally to ceramic materials formed from powder, and more particularly to hot-pressed structural materials comprising silicon nitride (Si3N4) wherein the oxygen content is controlled by maintaining the molar ratio of MgO and SiO2.
Inventors
- 👤 Frederick F. Lange
- 👤 Clarence A. Andersson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 18:38
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/515; C04B35/58; C04B35/584; C04B35/593
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
77 words
A structural material suitable for use at elevated temperatures consisting essentially of silicon nitride, silicon dioxide and magnesium oxide, the molar ratio of MgO to SiO 2 being within the range between about 3 and about 5, the MgO content not exceeding 6% by weight and the CaO content not exceeding 200 ppm, and the silicon nitride phases are between 83 and 93% alpha phase and between 7 and 17% beta phase and silicon is ≦ 1%.
Claim 2
Dependent Claim
77 words
A structural material suitable for use at elevated temperatures consisting essentially of silicon nitride, silicon dioxide and magnesium oxide, the molar ratio of MgO to SiO 2 being within the range between about 3 and about 5, the MgO content not exceeding 6% by weight and the CaO content not exceeding 200 ppm, and the silicon nitride phases are between 83 and 93% alpha phase and between 7 and 17% beta phase and silicon is ≦ 1%.
Claim 3
Dependent Claim
93 words
Hot pressed reaction sintered silicon nitride suitable for use at elevated temperatures consisting essentially of MgO, SiO 2 , Si, CaO and Si 3 N 4 with the MgO content not exceeding 6% by weight, the molar ratio of MgO to SiO 2 being within the range between about 3 and about 5, a silicon content ≦ 1% and the balance silicon nitride, said sintered nitride having a CaO content not exceeding 200 ppm, and the silicon nitride phases are between 83 and 93% alpha phase and between 7 and 17% beta phase.
Claim 4
Dependent Claim
93 words
Hot pressed reaction sintered silicon nitride suitable for use at elevated temperatures consisting essentially of MgO, SiO 2 , Si, CaO and Si 3 N 4 with the MgO content not exceeding 6% by weight, the molar ratio of MgO to SiO 2 being within the range between about 3 and about 5, a silicon content ≦ 1% and the balance silicon nitride, said sintered nitride having a CaO content not exceeding 200 ppm, and the silicon nitride phases are between 83 and 93% alpha phase and between 7 and 17% beta phase.
Claim 5
Dependent Claim
23 words
The composition of claim 2 in which the MgO to SiO 2 ratio is within the range between about 3 and about 4.
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) | 1981-07-10 | 1982-01-09 | 1982-07-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-07-10 | 1986-01-09 | 1986-07-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-07-10 | 1990-01-09 | 1990-07-11 | $7700.00 | Window Closed / Lapsed |