Patent US3772165A successfully refreshed from Google Patents.
US3772165A
Expired / Lapsed
US
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Method of treating surfaces of steel products
Assignee: JFE Engineering Corp
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Filing: 1972-01-10
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Granted: 1973-11-13
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Expires: 1992-01-10
Abstract
Abstract Method of treating the surfaces of metal products to provide protection against corrossive attack, comprising the steps of treating such metal products anodically in an aqueous electrolyte consisting of hexavalent chromium ions and borate ions and thereafter treating said metal products cathodically in an aqueous electrolyte consisting of hexavalent chromium ions and borate ions.
Inventors
- 👤 H Yamagishi
- 👤 N Gunji
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 19:48
CPC Classifications
C; C25; C25D; C25D11/00; C25D11/38
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
29 words
A method of treating metal products as described in claim 1 wherein the hexavalent chromium ions are present in said electrolyte in a concentration of 3 to 50 g/l.
Claim 2
Dependent Claim
32 words
A method of treating metal products as described in claim 1 wherein the concentration range of borate compounds which provide borate ions in said aqueous electrolyte is between 5 and 50 g/l.
Claim 3
Dependent Claim
60 words
A method as defined in claim 1 in which the metal article consists of a metal strip and the strip is electrolyzed in the bath by being passed between two counter electrodes that are immersed in the bath, the first of which serves as an anode and the second of which serves as a cathode with respect to the strip.
Claim 4
Dependent Claim
21 words
A method as defined in claim 1 in which the electrolyte is maintained at a temperature between 30* and 80* C.
Claim 5
Dependent Claim
24 words
A method of treating metal products according to claim 1 wherein the electrolyte is maintained at a pH value of from zero to six.
Claim 6
Dependent Claim
25 words
A method as defined in claim 1 in which the current applied during the cathodic electrolysis is between 1 and 300 coulombs per square decimeter.
Claim 7
Dependent Claim
39 words
A method of treating metal products as described in claim 1, wherein said metal products are treated anodically by the passage of between 0.1 and 30 coul/dm2 and subsequently treated cathodically by passage of between 1 and 300 coul/dm2.
Claim 8
Dependent Claim
30 words
A method as defined in claim 1 in which the electrolytic bath contains 20 grams per liter of sodium dichromate (Na2Cr2O7.2H2O) and 25 grams per liter of boric acid (H3BO3).
Claim 9
Dependent Claim
18 words
A process as defined in claim 4 in which the metal article is a tin-plated steel sheet material.
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) | 1976-11-12 | 1977-05-14 | 1977-11-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-11-12 | 1981-05-14 | 1981-11-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-11-12 | 1985-05-14 | 1985-11-13 | $7700.00 | Window Closed / Lapsed |