Patent US4309227A successfully refreshed from Google Patents.
US4309227A
Expired / Lapsed
US
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Ion-nitriding process
Assignee: Kawasaki Motors Ltd
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Filing: 1979-07-12
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Granted: 1982-01-05
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Expires: 1999-07-12
Abstract
Abstract Disclosed is an improved ion-nitriding process comprising ion-nitriding a workpiece at a high voltage level of glow discharge in a gas atmosphere resulting from the introduction of a gas mixture containing a specific amount of ammonia into a nitriding reactor, and then, further ion-nitriding the same workpiece at a lower voltage level of glow discharge in a gas atmosphere resulting from the introduction of a gas mixture not containing ammonia into the reactor.
Inventors
- 👤 Takashi Kajikawa
- 👤 Minoru Makimura
- 👤 Satoru Kunise
- 👤 Satoshi Furuitsu
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 18:02
CPC Classifications
C; C23; C23C; C23C8/00; C23C8/06; C23C8/36; C23C8/38
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
123 words
A process for ion-nitriding a metal workpiece by means of a glow discharge in a gas atmosphere containing nitrogen in a vacuum reactor, comprising the steps of ion-nitriding the workpiece at a high voltage level of glow discharge in a gas resulting from the introduction, into the reactor, of a gas mixture of nitrogen, hydrogen and ammonia in which the amount of the ammonia is at least 20% by volume, replacing the gas atmosphere with a gas mixture containing nitrogen and hydrogen but not containing ammonia and then further ion-nitriding the same workpiece at a lower voltage level of glow discharge in the gas atmosphere resulting from the introduction, into the reactor, of the gas mixture of nitrogen and hydrogen not containing ammonia.
Claim 2
Dependent Claim
123 words
A process for ion-nitriding a metal workpiece by means of a glow discharge in a gas atmosphere containing nitrogen in a vacuum reactor, comprising the steps of ion-nitriding the workpiece at a high voltage level of glow discharge in a gas resulting from the introduction, into the reactor, of a gas mixture of nitrogen, hydrogen and ammonia in which the amount of the ammonia is at least 20% by volume, replacing the gas atmosphere with a gas mixture containing nitrogen and hydrogen but not containing ammonia and then further ion-nitriding the same workpiece at a lower voltage level of glow discharge in the gas atmosphere resulting from the introduction, into the reactor, of the gas mixture of nitrogen and hydrogen not containing ammonia.
Claim 3
Dependent Claim
54 words
A process as claimed in claim 3 in which the voltage level of glow discharge in the first ion-nitriding step is 560 V and that in the second ion-nitriding step is 450 V, and in which the ratio of nitrogen to hydrogen in the gas mixture introduced in both of the steps is 1:3.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1985-01-04 | 1985-07-06 | 1986-01-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-01-04 | 1989-07-06 | 1990-01-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-01-04 | 1993-07-06 | 1994-01-05 | $7700.00 | Window Closed / Lapsed |