US4495122A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for the production of a polycrystalline shaped body of silicon carbide
Assignee: Feldmuehle AG
•
Filing: 1981-11-23
•
Granted: 1985-01-22
•
Expires: 2001-11-23
Abstract
Abstract Method for the production of a polycrystalline shaped body of silicon carbide of a density of at least 98% of the theoretical density of silicon carbide, prepared through pressureless sintering at temperatures from 1,900 to 2,200 C. from at least 97 weight % of α-silicon carbide and/or β-silicon carbide under addition of up to 3 weight % of boron, characterized by the fact that the shaped body is prepared without any carbon additions to the batch and is pressureless sintered in a carbon containing protective gas atmosphere.
Inventors
- 👤 Gerhard Leimer
- 👤 Ernst Gugel
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 00:50
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/515; C04B35/56; C04B35/565; C04B35/575
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
88 words
In a method for the production of a polycrystalline shaped body of silicon carbide of a density of at least 98% of the theoretical density of silicon carbide, prepared through pressureless sintering at temperatures from 1,900° to 2,200° C. from at least 97 weight % of α-silicon carbide or β-silicon carbide under addition of up to 3 weight % of boron, the improvement which comprises said shaped body being prepared without any carbon additions to the batch and being pressureless sintered in a carbon containing protective gas atmosphere.
Claim 2
Dependent Claim
88 words
In a method for the production of a polycrystalline shaped body of silicon carbide of a density of at least 98% of the theoretical density of silicon carbide, prepared through pressureless sintering at temperatures from 1,900° to 2,200° C. from at least 97 weight % of α-silicon carbide or β-silicon carbide under addition of up to 3 weight % of boron, the improvement which comprises said shaped body being prepared without any carbon additions to the batch and being pressureless sintered in a carbon containing protective gas atmosphere.
Claim 3
Dependent Claim
15 words
The method of claim 1, wherein the carbon containing protective gas atmosphere contains pyrolysable hydrocarbons.
Claim 4
Dependent Claim
57 words
The method of claim 1, wherein the silicon carbide powder used is a powder with a specific surface area between 10 and 20 m 2 /g in which at least 95% of the grains are below 1 μm in size and which is free of impurities that reduce to metals and are liquid at the sintering temperatures.
Claim 5
Dependent Claim
18 words
The method of claim 1 or 2, wherein the shaped body is subjected to a hot isostatic aftertreatment.
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) | 1988-01-22 | 1988-07-23 | 1989-01-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-01-22 | 1992-07-23 | 1993-01-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-01-22 | 1996-07-23 | 1997-01-22 | $7700.00 | Window Closed / Lapsed |