US5141567A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of nitriding steel
Assignee: Air Water Inc
•
Filing: 1991-01-22
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Granted: 1992-08-25
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Expires: 2011-01-22
Abstract
Abstract Steel is nitrided first by treating the steel to be nitrided with NF 3 at elevated temperatures to form a fluorinated layer on the steel, and then the steel is nitrided by heating in a nitriding atmosphere.
Inventors
- 👤 Masaaki Tahara
- 👤 Takakazu Tomoda
- 👤 Kenzo Kitano
- 👤 Teruo Minato
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 04:16
CPC Classifications
C; C23; C23C; C23C8/00; C23C8/02; C23C8/06; C23C8/08; C23C8/24; C23C8/26; C23C8/34
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
58 words
A method of nitriding steel which comprises treating the steel with NF 3 gas at a temperature over 350° C. and not more than 500° C. to form a fluorinated layer on the surface of the steel, and then heating the fluorinated steel at 480-700° C. in a nitriding atmosphere to form a nitrided layer on the steel.
Claim 2
Independent Claim
58 words
A method of nitriding steel which comprises treating the steel with NF 3 gas at a temperature over 350° C. and not more than 500° C. to form a fluorinated layer on the surface of the steel, and then heating the fluorinated steel at 480-700° C. in a nitriding atmosphere to form a nitrided layer on the steel.
References Cited (Backward Citations)
US5013371A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1995-08-25 | 1996-02-24 | 1996-08-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-08-25 | 2000-02-24 | 2000-08-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-08-25 | 2004-02-24 | 2004-08-25 | $7700.00 | Window Closed / Lapsed |