Patent US3835211A successfully refreshed from Google Patents.
US3835211A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Silicon nitride products
Assignee: ZF International UK Ltd
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Filing: 1972-04-06
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Granted: 1974-09-10
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Expires: 1992-04-06
Abstract
Abstract A method of manufacturing silicon nitride products is of the kind in which silicon nitride powder is pressed at an elevated temperature to form the product, the pressing being continued until the product is fully densified. The method is characterised in that the fully densified product is then heated further at a temperature sufficient to convert Alpha -phase silicon nitride to Beta -phase silicon nitride.
Inventors
- 👤 R Coe
- 👤 R Lumby
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 10:23
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/515; C04B35/58; C04B35/584; C04B35/593
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
38 words
A method as claimed in claim 1 wherein said fully densified product remains under compression whilst the product is retained in the die at the temperature sufficient to convert Alpha -phase silicon nitride to Beta -phase silicon nitride.
Claim 2
Independent Claim
63 words
A method of manufacturing a silicon nitride product comprising pressing silicon nitride powder in a die at an elevated temperature to form a product which is fully densified at the pressure applied, removing the fully densified product from the die, and heating the product in a separate furnace at a temperature sufficient to convert Alpha -phase silicon nitride to Beta -phase silicon nitride.
Claim 3
Dependent Claim
23 words
A method as claimed in claim 3 wherein said fully densified product is compressed whilst the product is heated in the separate furnace.
References Cited (Backward Citations)
US3409417A
Cited
GB1092637A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-09-09 | 1978-03-11 | 1978-09-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-09-09 | 1982-03-11 | 1982-09-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-09-09 | 1986-03-11 | 1986-09-10 | $7700.00 | Window Closed / Lapsed |