Patent US4141759A successfully refreshed from Google Patents.
US4141759A
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Process for the formation of an anticorrosive, oxide layer on maraging steels
Assignee: Uranit GmbH
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Filing: 1976-01-20
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Granted: 1979-02-27
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Expires: 1996-01-20
Abstract
Abstract A method is provided for forming an anti-corrosive, oxide layer on steel. The steel surface is subjected to superheated steam for a period of one to several hours. Before subjecting the steel to the superheated steam, a clean steel surface is initially heated to at least 200° C. in a nitrogen, air, or oxygen atmosphere. The treatment with superheated steam takes place during a further heating period in which a temperature between 450° C. and 520° C. is reached and maintained under steam flow through conditions in which the steam flow is turbulent or should have a Reynolds number greater than 900.
Inventors
- 👤 Martin Pfistermeister
- 👤 Heinz Krapf
- 👤 Erwin Coester
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 15:52
CPC Classifications
C; C23; C23C; C23C8/00; C23C8/06; C23C8/08; C23C8/10; C23C8/16; C23C8/18
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
117 words
In a process for forming an anti-corrosive oxide layer on maraging steel, in which the steel surface is subjected to superheated steam for a period of at least one hour, the improvement comprising heating a clean maraging steel surface to a temperature between 200° C. and 250° C. in a nitrogen, air or oxygen atmosphere in the absence of superheated steam, and then subjecting the heated maraging steel to a further heating period in which a temperature between 450° C. and 520° C. is reached and maintained, with superheated steam under flow conditions in which the flow has a Reynolds number of greater than 900 to form an anti-corrosive oxide layer which is a mixed oxide layer.
Claim 2
Dependent Claim
117 words
In a process for forming an anti-corrosive oxide layer on maraging steel, in which the steel surface is subjected to superheated steam for a period of at least one hour, the improvement comprising heating a clean maraging steel surface to a temperature between 200° C. and 250° C. in a nitrogen, air or oxygen atmosphere in the absence of superheated steam, and then subjecting the heated maraging steel to a further heating period in which a temperature between 450° C. and 520° C. is reached and maintained, with superheated steam under flow conditions in which the flow has a Reynolds number of greater than 900 to form an anti-corrosive oxide layer which is a mixed oxide layer.
Claim 3
Dependent Claim
29 words
The method as defined in claim 1 wherein, after the steam treatment the steel is cooled for several hours in a stream of nitrogen or air with regulatable temperature.
Claim 4
Dependent Claim
19 words
The method as defined in claim 2 wherein the steel is cooled to a temperature of about 100° C.
Claim 5
Dependent Claim
20 words
The method as defined in claim 2 wherein the heating and cooling are effected in a regulatable fluidized bed furnace.
Claim 6
Dependent Claim
18 words
The method as defined in claim 1 wherein the heating is effected in a regulatable fluidized bed furnace.
Claim 7
Dependent Claim
17 words
The method as defined in claim 1 wherein the superheated steam flow is as turbulent as possible.
Claim 8
Dependent Claim
17 words
The method as defined in claim 1 wherein the Reynolds number is from about 2100 to 2500.
Claim 9
Dependent Claim
41 words
The method as defined in claim 1 wherein the oxide layer comprises mixed and pure spinels of Fe(Fe 2 O 4 ), Ni(Fe 2 O 4 ), Ni(Co 2 O 4 ), Co(Co 2 O 4 ) and FeMoO 4 .
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1982-02-26 | 1982-08-28 | 1983-02-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-02-26 | 1986-08-28 | 1987-02-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-02-26 | 1990-08-28 | 1991-02-27 | $7700.00 | Window Closed / Lapsed |