Patent US4038092A successfully refreshed from Google Patents.
US4038092A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Strengthening reaction sintered silicon nitride
Assignee: Saint Gobain Abrasives Inc
•
Filing: 1976-01-30
•
Granted: 1977-07-26
•
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 14:38
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
Cited
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 |