US4236942A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for the gaseous nitriding of ferrous-based components
Assignee: Rover Co Ltd
•
Filing: 1978-05-23
•
Granted: 1980-12-02
•
Expires: 1998-05-23
Abstract
Abstract A ferrous-based component is nitrided by subjecting the heated component to an atmosphere of ammonia and then to an atmosphere of an inert gas. The undesirable nitrogen-rich layer which was hitherto produced at the surface of the component in nitriding is reduced or eliminated in the process of the invention.
Inventors
- 👤 Frederick V. Rudd
- 👤 Tom Bracewell, deceased
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 15:34
CPC Classifications
C; C23; C23C; C23C8/00; C23C8/06; C23C8/08; C23C8/24; C23C8/26
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
103 words
A method of nitriding a ferrous-base alloy component which comprises subjecting the heated component, which has previously been subjected when heated to an atmosphere of ammonia, whereby a nitrided case layer and an iron nitride skin was produced, to an atmosphere of gas inert to the component at the temperature of the component in the inert gas, the temperature of the component in the inert gas lying between 450° C. and 600° C. and the component being subjected to the inert gas for at least twenty hours, whereby the iron nitride skin is at least partly removed without destroying the nitrided case layer.
Claim 2
Independent Claim
103 words
A method of nitriding a ferrous-base alloy component which comprises subjecting the heated component, which has previously been subjected when heated to an atmosphere of ammonia, whereby a nitrided case layer and an iron nitride skin was produced, to an atmosphere of gas inert to the component at the temperature of the component in the inert gas, the temperature of the component in the inert gas lying between 450° C. and 600° C. and the component being subjected to the inert gas for at least twenty hours, whereby the iron nitride skin is at least partly removed without destroying the nitrided case layer.
Claim 3
Dependent Claim
17 words
A method as claimed in claim 1 wherein the temperature lies between 490° C. and 550° C.
Claim 4
Dependent Claim
22 words
A method as claimed in claim 1 wherein the component is subjected to the inert gas for between 20 and 60 hours.
Claim 5
Dependent Claim
13 words
A method as claimed in claim 1 wherein the inert gas is nitrogen.
Claim 6
Dependent Claim
16 words
A method as claimed in claim 1 wherein the inert gas is fed past the component.
Claim 7
Dependent Claim
36 words
A method as claimed in claim 1 wherein the steps of subjecting the component to the ammonia and of subjecting the component to the inert gas are carried out consecutively, the inert gas replacing the ammonia.
Claim 8
Dependent Claim
23 words
A method according to claim 1 further comprising cooling the component to room temperature in an atmosphere of gas inert to the component.
Claim 9
Independent Claim
115 words
A method of nitriding a ferrous-base alloy component which comprises subjecting the component to an atmosphere of ammonia while the component is at a temperature between 450° C. and 600° C. to produce a nitrided case layer and an iron nitride skin on the component, and then subjecting the component to an atmosphere of gas inert to the component at the temperature of the component in the inert gas, the temperature of the component in the inert gas lying between 450° C. and 600° C. and the component being subjected to the inert gas for at least twenty hours, whereby the iron nitride skin is at least partly removed without destroying the nitrided case layer.
Claim 10
Independent Claim
115 words
A method of nitriding a ferrous-base alloy component which comprises subjecting the component to an atmosphere of ammonia while the component is at a temperature between 450° C. and 600° C. to produce a nitrided case layer and an iron nitride skin on the component, and then subjecting the component to an atmosphere of gas inert to the component at the temperature of the component in the inert gas, the temperature of the component in the inert gas lying between 450° C. and 600° C. and the component being subjected to the inert gas for at least twenty hours, whereby the iron nitride skin is at least partly removed without destroying the nitrided case layer.
Claim 11
Dependent Claim
21 words
A method as claimed in claim 8 wherein the component is subjected to the ammonia for between 20 and 60 hours.
References Cited (Backward Citations)
US1647847A
Cited
US3219494A
Cited
US3265541A
Cited
US3399085A
Cited
US3377214A
Cited
US3998666A
Cited
US4011111A
Cited
US4046601A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1983-12-02 | 1984-06-02 | 1984-12-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-12-02 | 1988-06-02 | 1988-12-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-12-02 | 1992-06-02 | 1992-12-02 | $7700.00 | Window Closed / Lapsed |