Patent US3455729A successfully refreshed from Google Patents.
US3455729A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Silicon nitride
Assignee: Plessey Overseas Ltd
•
Filing: 1965-11-24
•
Granted: 1969-07-15
•
Expires: 1985-11-24
Abstract
Abstract Silicon nitride bodies are subjected to Li2O vapour, e.g for 3 to 200 hours at 500-1500 DEG C., to improve their resistance to thermal shocks. The Li2O may be obtained by heating LiOH, a 2% solution of which may be absorbed in a porous alumina brick located close to the silicon nitride body to be treated. The surface of the treated body can be etched away with HF.
Inventors
- 👤 Gerald G Deeley
- 👤 John M Herbert
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 22:19
CPC Classifications
C; C04; C04B; C04B41/00; C04B41/009; C04B35/00; C04B35/515; C04B35/58; C04B35/584; C04B41/45; C04B41/50; C04B41/80; C04B41/81; C04B41/85
Claims Analysis
Total Claims: 0
No claims parsed yet. Click Sync Now above to re-index claims from Google Patents.
References Cited (Backward Citations)
US3226194A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1972-07-14 | 1973-01-13 | 1973-07-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1976-07-14 | 1977-01-13 | 1977-07-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1980-07-14 | 1981-01-13 | 1981-07-15 | $7700.00 | Window Closed / Lapsed |