US3850767A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electrolytic treatment of stainless steel having an oxidic film
Assignee: Huntington Alloys Corp
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Filing: 1972-10-27
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Granted: 1974-11-26
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Expires: 1992-10-27
Abstract
Abstract Oxidic films on stainless steel and similar alloys formed by treatment of the alloys in aqueous solutions of sulfuric acid and pitting inhibiting oxidizing agents, are hardened by being treated as cathodes in aqueous electrolytes containing metal ion having a pH in excess of about 0.5 and within the range for the particular metal of the solution whereby oxide will form at the cathode rather than metal.
Inventors
- 👤 A Skedgell
- 👤 V Smith
- 👤 T Evans
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 14:50
CPC Classifications
C; C22; C22C; C22C18/00; C22C18/04; C22F; C22F1/00; C22F1/16; C22F1/165
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
109 words
A PROCESS FOR HARDENING AN OXIDIC FILM ON IRON-BASE, CHROMIUM-CONTAINING, CORROSION-RESISTANT ALLOY FORMED BY TREATMENT OF SAID ALLOY IN AN AQUEOUS SOLUTION OF SULFURIC ACID AND CHROMIC ACID WHICH PROCESS COMPRISES TREATING SAID ALLOY HAVING SAID FILM ON THE SURFACE THEREOF AS A CATHODE IN AN AQUEOUS SOLUTION HAVING A PH IN EXCESS OF ABOUT 0.5, CONTAINING IN IONIC FORM METAL FROM THE GROUP CONSISTING OF ALUMINUM, TITANIUM, VANADIUM, CHROMIUM, MOLYBDENUM, TUNGSTEN, MANGANESE, IRON, COBALT, NICKEL, COPPER, ZINC, TIN AND SILICON AND HAVING THE PH REGULATED WITHIN A SPECIAL RANGE FOR EACH TYPE OF ION SO THAT OXIDE WILL BE DEPOSITED AT SAID CAHODIC SURFACE IN PREFERENCE TO METAL.
Claim 2
Dependent Claim
109 words
A PROCESS FOR HARDENING AN OXIDIC FILM ON IRON-BASE, CHROMIUM-CONTAINING, CORROSION-RESISTANT ALLOY FORMED BY TREATMENT OF SAID ALLOY IN AN AQUEOUS SOLUTION OF SULFURIC ACID AND CHROMIC ACID WHICH PROCESS COMPRISES TREATING SAID ALLOY HAVING SAID FILM ON THE SURFACE THEREOF AS A CATHODE IN AN AQUEOUS SOLUTION HAVING A PH IN EXCESS OF ABOUT 0.5, CONTAINING IN IONIC FORM METAL FROM THE GROUP CONSISTING OF ALUMINUM, TITANIUM, VANADIUM, CHROMIUM, MOLYBDENUM, TUNGSTEN, MANGANESE, IRON, COBALT, NICKEL, COPPER, ZINC, TIN AND SILICON AND HAVING THE PH REGULATED WITHIN A SPECIAL RANGE FOR EACH TYPE OF ION SO THAT OXIDE WILL BE DEPOSITED AT SAID CAHODIC SURFACE IN PREFERENCE TO METAL.
Claim 3
Dependent Claim
15 words
A process as in claim 1 wherein the iron-base, chromium-containing, corrosion-resistant alloy is stainless steel.
Claim 4
Dependent Claim
40 words
A process as in claim 2 wherein the aqueous solution contains about 0.25 to about 7.5 moles per liter of CrO3, and sufficient base to maintain the pH of the solution in the range of about 3 to about 7.5.
Claim 5
Dependent Claim
19 words
A process as in claim 3 wherein the aqueous solution has a pH of about 6.3 to about 7.5.
Claim 6
Dependent Claim
29 words
A process as in claim 1 wherein the metal ion in aqueous solution is hexavalent chromium and the pH is in the range of about 3 to about 7.5.
Claim 7
Dependent Claim
16 words
A process as in claim 1 wherein the metal ion in aqueous solution is trivalent aluminum.
Claim 8
Dependent Claim
15 words
A process as in claim 1 wherein the metal ion in solution is heptavalent manganese.
Claim 9
Dependent Claim
15 words
A process as in claim 1 wherein the metal ion in solution is divalent nickel.
Claim 10
Dependent Claim
15 words
A process as in claim 1 wherein the metal ion in solution is divalent zinc.
References Cited (Backward Citations)
US3535213A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-11-25 | 1978-05-27 | 1978-11-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-11-25 | 1982-05-27 | 1982-11-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-11-25 | 1986-05-27 | 1986-11-26 | $7700.00 | Window Closed / Lapsed |