US4312899A
Expired / Lapsed
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Process for the production of oxidation-resistant sintered silicon nitride bodies with improved mechanical strength
Assignee: Daimler Benz AG
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Filing: 1980-09-30
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Granted: 1982-01-26
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Expires: 2000-09-30
Abstract
Abstract A process for the production of oxidation-resistant sintered silicon nitride bodies having improved mechanical strength involves dissolving aluminum oxide, aluminum nitride, or mixtures thereof by diffusion in the surface of the sintered silicon nitride bodies. The diffusion is effected by embedding the bodies within powder of aluminum oxide, aluminum nitride or mixture thereof and by heating the embedded bodies to a temperature of at least 1300° C.
Inventors
- 👤 Claus-Peter Lahmann
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 08:07
CPC Classifications
C; C04; C04B; C04B41/00; C04B41/009; C04B35/00; C04B35/515; C04B35/58; C04B35/584; C04B35/593; C04B41/45; C04B41/50; C04B41/5025; C04B41/5031; C04B41/80; C04B41/81; C04B41/85; C04B41/87
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
51 words
A process for the production of oxidation-resistant sintered silicon nitride bodies having improved mechanical strength, characterized in that a material consisting essentially of aluminum oxide, alumininum nitride, or mixtures thereof is dissolved by diffusion in the surface of the sintered silicon nitride bodies at temperatures of not more than 1900° C.
Claim 2
Dependent Claim
51 words
A process for the production of oxidation-resistant sintered silicon nitride bodies having improved mechanical strength, characterized in that a material consisting essentially of aluminum oxide, alumininum nitride, or mixtures thereof is dissolved by diffusion in the surface of the sintered silicon nitride bodies at temperatures of not more than 1900° C.
Claim 3
Dependent Claim
45 words
A process according to claim 1, characterized in that the diffusion is executed by annealing the sintered silicon nitride bodies for 3-40 hours in a powder consisting essentially of aluminum oxide powder, aluminum nitride powder or mixtures thereof at temperatures of 1300° C. and above.
Claim 4
Dependent Claim
23 words
A process according to claim 2, characterized in that the annealing step is conducted in an atmosphere inert with respect to silicon nitride.
Claim 5
Dependent Claim
18 words
A process according to claim 3, characterized in that the inert atmosphere consists of nitrogen and/or noble gases.
Claim 6
Dependent Claim
66 words
A process according to claim 1, wherein the diffusion of the material is effected by embedding the sintered nitride bodies within finely divided powder of said material, and by heating the embedded bodies and powder to a temperature ranging from 1300° to not more than 1900° C. within a vacuum or an atmosphere inert to the silicon nitride for a period of at least 3 hours.
Claim 7
Dependent Claim
27 words
A process according to claim 1, wherein the diffusion is effected at a temperature of from 1340° to 1600° C. for a period of from 30-80 hours.
Claim 8
Dependent Claim
40 words
A process according to claim 1, wherein the diffusion is effected for a period of time and at a temperature of at least 1300° C. to provide a protective surface layer on the silicon nitride bodies of about 10 μm.
Claim 9
Dependent Claim
28 words
A process according to claim 1, wherein the diffusion is effected by embedding the individual silicon nitride bodies within a finely divided aluminum oxide powder and by heating.
Claim 10
Dependent Claim
29 words
A process according to claim 1, wherein the diffusion is effected by embedding the individual silicon nitride bodies within a finely divided powder of aluminum nitride and by heating.
Claim 11
Dependent Claim
21 words
A process according to claim 8 or claim 9 wherein the powder has a particle size of 20 μm or less.
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) | 1985-01-25 | 1985-07-27 | 1986-01-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-01-25 | 1989-07-27 | 1990-01-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-01-25 | 1993-07-27 | 1994-01-26 | $7700.00 | Window Closed / Lapsed |