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Patent US4460415A successfully refreshed from Google Patents.
US4460415A
Expired / Lapsed
US
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Method for nitriding materials at low pressures using a glow discharge
Assignee: ABB Stromberg Oy
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Filing: 1982-09-21
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Granted: 1984-07-17
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Expires: 2002-09-21
Abstract
Abstract A method for nitriding materials using a glow discharge in an atmosphere of nitrogen or gas mixture at a pressure between 1 . . . 100 mtorr (0.13 . . . 13.3 Pa). Nitriding treatment can be combined with a plasma aided coating process and the temperature control during both processes can be achieved with the aid of separate filament. Nitriding unit can be a separate rig or a part of the coating unit. The method can be used to increase the wear resistance of a work piece by increasing the hardness of its surface. Because of the low pressure used in the nitriding process the same equipment can be used to produce a separate hard and wear resistant compound or alloy coating on the nitrided surface to further increase the hardness of the uppermost surface. The main field of the method is in increasing the wear and corrosion resistance of machine parts and tools.
Inventors
- 👤 Antti S. Korhonen
- 👤 Eero H. Sirvio
- 👤 Martti S. Sulonen
- 👤 Heikki A. Sundquist
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 15:38
CPC Classifications
C; C23; C23C; C23C28/00; C23C8/00; C23C8/06; C23C8/36
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
54 words
A method for nitriding work pieces with the aid of a glow discharge of nitrogen or a gas mixture containing nitrogen, comprising applying a gas pressure of from 1 to 100 mtorr and controlling the temperature of the work piece and the ion current to the work piece by a separate negatively biased filament.
Claim 2
Independent Claim
54 words
A method for nitriding work pieces with the aid of a glow discharge of nitrogen or a gas mixture containing nitrogen, comprising applying a gas pressure of from 1 to 100 mtorr and controlling the temperature of the work piece and the ion current to the work piece by a separate negatively biased filament.
Claim 3
Dependent Claim
27 words
A method as claimed in claim 1 applied in combination with ion plating or another comparable plasma aided coating method or preceeding or following such a treatment.
Claim 4
Dependent Claim
144 words
In a method for nitriding a surface of a work piece located in a chamber which method includes providing in the chamber a gaseous atmosphere containing nitrogen cathodically connecting the work piece to a high voltage source and anodically connecting the chamber to the source to produce a glow discharge and an ion current between the work piece and the chamber whereby the work piece is heated and whereby nitrogen diffuses into a surface of the work piece, the improvement which comprises adjusting the pressure of the nitrogen-containing atmosphere to the range 1 to 100 mtorr, and controlling the temperature of the work piece and the ion current to the work piece by providing in the chamber a heated filament and negatively biasing the filament by electrically connecting it to a voltage source separate from the power source which negatively charges the work piece.
Claim 5
Dependent Claim
144 words
In a method for nitriding a surface of a work piece located in a chamber which method includes providing in the chamber a gaseous atmosphere containing nitrogen cathodically connecting the work piece to a high voltage source and anodically connecting the chamber to the source to produce a glow discharge and an ion current between the work piece and the chamber whereby the work piece is heated and whereby nitrogen diffuses into a surface of the work piece, the improvement which comprises adjusting the pressure of the nitrogen-containing atmosphere to the range 1 to 100 mtorr, and controlling the temperature of the work piece and the ion current to the work piece by providing in the chamber a heated filament and negatively biasing the filament by electrically connecting it to a voltage source separate from the power source which negatively charges the work piece.
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) | 1987-07-17 | 1988-01-16 | 1988-07-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-07-17 | 1992-01-16 | 1992-07-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-07-17 | 1996-01-16 | 1996-07-17 | $7700.00 | Window Closed / Lapsed |