US2171391A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process of producing hard materials
Assignee: Firm Duradur S A
•
Filing: 1937-03-19
•
Granted: 1939-08-29
•
Expires: 1957-03-19
Abstract
No abstract record available.
Inventors
- 👤 Boecker Alfred
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 22:16
CPC Classifications
C; C22; C22C; C22C1/00; C22C1/04; C22C1/05; C22C1/051; C22C1/053; C22C1/055
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) | 1942-08-28 | 1943-02-27 | 1943-08-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1946-08-28 | 1947-02-27 | 1947-08-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1950-08-28 | 1951-02-27 | 1951-08-29 | $7700.00 | Window Closed / Lapsed |