Patent US3591668A successfully refreshed from Google Patents.
US3591668A
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Strengthening fully sintered alumina and titania articles by reheating in a fluorine atmosphere
Assignee: HENRY P KIRCHNER
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Filing: 1968-05-28
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Granted: 1971-07-06
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Expires: 1988-05-28
Abstract
Abstract ALUMINA AND TITANIA BODIES WHICH HAVE PREVIOUSLY BEEN FULLY SINTERED BY CONVENTIONAL TECHNIQUES ARE REHEATED TO AT LEAST 1400*C. IN AN ATMOSPHERE CONTAINING AT LEAST 20% FLUORINE FOR A PERIOD OF ABOUT 1-4 HOURS TO SUBSTANTIALLY IMPROVE THEIR STRENGTH.
Inventors
- 👤 Henry P Kirchner
- 👤 Ralph E Walker
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 13:04
CPC Classifications
C; C04; C04B; C04B41/00; C04B41/009; C04B35/00; C04B35/01; C04B35/10; C04B35/46; C04B41/45; C04B41/50; C04B41/5018; C04B41/5019; C04B41/80; C04B41/81; C04B41/85
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-07-05 | 1975-01-04 | 1975-07-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-07-05 | 1979-01-04 | 1979-07-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-07-05 | 1983-01-04 | 1983-07-06 | $7700.00 | Window Closed / Lapsed |