US4038092A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Strengthening reaction sintered silicon nitride
Assignee: Saint Gobain Abrasives Inc
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Filing: 1976-01-30
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Granted: 1977-07-26
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Expires: 1996-01-30
Abstract
Abstract The strength of a reaction sintered silicon nitride body is substantially increased by impregnating the surface of the body with finely divided alumina and then firing the body in a nitrogen atmosphere to a temperature in excess of 1200° C, the reaction being carried out under an appreciable partial pressure of SiO.
Inventors
- 👤 Hans R. Baumgartner
- 👤 Stephen D. Skrovanek
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 12:45
CPC Classifications
C; C04; C04B; C04B41/00; C04B41/009; C04B35/00; C04B35/515; C04B35/58; C04B35/584; C04B35/591; C04B35/597; C04B41/45; C04B41/50; C04B41/5053; C04B41/5062; C04B41/5067; C04B41/80; C04B41/81; C04B41/85; C04B41/87
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
67 words
In a process for increasing the strength of a previously formed reaction sintered silicon nitride body wherein the surface of the formed body is impregnated with a aluminum oxide (Al 2 O 3 ) and fired in a nitrogen atmosphere at a temperature between about 1200° and about 1500° C., the improvement which comprises maintaining a substantial partial pressure of SiO in the atmosphere during said firing.
Claim 2
Dependent Claim
67 words
In a process for increasing the strength of a previously formed reaction sintered silicon nitride body wherein the surface of the formed body is impregnated with a aluminum oxide (Al 2 O 3 ) and fired in a nitrogen atmosphere at a temperature between about 1200° and about 1500° C., the improvement which comprises maintaining a substantial partial pressure of SiO in the atmosphere during said firing.
Claim 3
Dependent Claim
57 words
In a process for increasing the strength of a previously formed reaction sintered silicon nitride body wherein the surface of the formed body is impregnated with aluminum oxide and fired in a nitrogen atmosphere at a temperature above 1200° C., the improvement which comprises maintaining a substantial partial pressure of SiO in the atmosphere during said firing.
Claim 4
Dependent Claim
57 words
In a process for increasing the strength of a previously formed reaction sintered silicon nitride body wherein the surface of the formed body is impregnated with aluminum oxide and fired in a nitrogen atmosphere at a temperature above 1200° C., the improvement which comprises maintaining a substantial partial pressure of SiO in the atmosphere during said firing.
Claim 5
Dependent Claim
30 words
The process of claim 1 wherein the partial pressure of SiO is generated by heating a mixture of Si and SiO 2 to a temperature of at least 1200° C.
Claim 6
Dependent Claim
21 words
The process of claim 1 wherein the firing temperature does not exceed 1400° C. during early portions of the firing cycle.
Claim 7
Dependent Claim
9 words
The product resulting from the process of claim 2.
References Cited (Backward Citations)
US3222438A
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US3409417A
Cited
US3427373A
Cited
US3535154A
Cited
US3639101A
Cited
US3824120A
Cited
US3903230A
Cited
FR2221421B3
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-07-25 | 1981-01-24 | 1981-07-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-07-25 | 1985-01-24 | 1985-07-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-07-25 | 1989-01-24 | 1989-07-26 | $7700.00 | Window Closed / Lapsed |