US4492765A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Si3 N4 ceramic articles having lower density outer layer, and method
Assignee: Osram Sylvania Inc
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Filing: 1980-08-15
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Granted: 1985-01-08
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Expires: 2000-08-15
Abstract
Abstract Monolithic Si 3 N 4 ceramic bodies having a lower density outer layer are produced by a one-step sintering in an ambient atmosphere of water vapor and a nonreactive diluent gas, and are useful, for example, as abradable seal and impact resistant structural elements.
Inventors
- 👤 Sergej-Tomislav Buljan
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 06:59
CPC Classifications
F; F01; F01D; F01D11/00; F01D11/08; F01D11/12; F01D11/122; C; C04; C04B; C04B35/00; C04B35/515; C04B35/58; C04B35/584; C04B35/622; C04B35/64; Y; Y10; Y10T; Y10T428/00; Y10T428/24; Y10T428/24942; Y10T428/24992
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
33 words
A dense monolithic Si 3 N 4 ceramic body, characterized in that at least a portion of the body has an outer layer exhibiting a lower density than the interior of the body.
Claim 2
Dependent Claim
33 words
A dense monolithic Si 3 N 4 ceramic body, characterized in that at least a portion of the body has an outer layer exhibiting a lower density than the interior of the body.
Claim 3
Dependent Claim
51 words
The body of claim 1 containing up to 25 weight percent of a densifying additive selected from the group consisting of MgO, CrN, Y 2 O 3 , La 2 O 3 , ZrO 2 , ZrN, HfO 2 , CeO 2 , Al 2 O 3 and SiO 2 .
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-01-08 | 1988-07-09 | 1989-01-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-01-08 | 1992-07-09 | 1993-01-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-01-08 | 1996-07-09 | 1997-01-08 | $7700.00 | Window Closed / Lapsed |