Patent US3935084A successfully refreshed from Google Patents.
US3935084A
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Anodizing process
Assignee: Sumitomo Light Metal Industries Ltd
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Filing: 1974-03-28
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Granted: 1976-01-27
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Expires: 1994-03-28
Abstract
Abstract A colored oxide film on the surface of aluminium or an alloy thereof can be formed by anodizing at a D.C. voltage in an electrolyte based on sulfuric acid, followed by alternating current electrolysis at an A.C. voltage which is lower than the D.C. voltage. In order to increase the degree of coloring of the colored oxide film, after the alternating current electrolysis the A.C. voltage is raised to a higher level but lower than the D.C. voltage, followed by dropping the voltage down to a level of the A.C. voltage or thereabout.
Inventors
- 👤 Shiro Terai
- 👤 Akinari Ichiryu
- 👤 Toshio Suzuki
- 👤 Yoshikatsu Hayashi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 10:01
CPC Classifications
C; C25; C25D; C25D11/00; C25D11/02; C25D11/04; C25D11/14; C25D11/18; C25D11/20; C25D11/22
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
124 words
A process of forming a colored oxide film on a substrate of aluminium or an aluminium alloy, which comprises subjecting the substrate to anodizing at a direct-current voltage E 1 of 10 to 20 volts in an electrolyte comprising an aqueous solution of 4 to 15% by weight of sulfuric acid to form a substantially colorless oxide film on the surface of the substrate, then dropping the voltage E 1 to zero and subjecting the substrate carrying the oxide film on its surface to electrolytic treatment in the same electrolyte by applying an alternating-current voltage E 2 of 2 to 4 volts for a period of 2 to 20 minutes to develop a recovery effect and obtain an oxide film of desired color tone.
Claim 2
Dependent Claim
124 words
A process of forming a colored oxide film on a substrate of aluminium or an aluminium alloy, which comprises subjecting the substrate to anodizing at a direct-current voltage E 1 of 10 to 20 volts in an electrolyte comprising an aqueous solution of 4 to 15% by weight of sulfuric acid to form a substantially colorless oxide film on the surface of the substrate, then dropping the voltage E 1 to zero and subjecting the substrate carrying the oxide film on its surface to electrolytic treatment in the same electrolyte by applying an alternating-current voltage E 2 of 2 to 4 volts for a period of 2 to 20 minutes to develop a recovery effect and obtain an oxide film of desired color tone.
Claim 3
Dependent Claim
54 words
A process as claimed in claim 1, which further comprises raising the voltage E 2 to a higher voltage E 3 in the range 5 to 10 volts and suddenly dropping the voltage E 3 after applying it for a period of seconds down to a voltage within the range of E 2 .
Claim 4
Dependent Claim
24 words
A process as claimed in claim 2, which further comprises repeating the voltage cycle of the rise and the drop once or more times.
Claim 5
Dependent Claim
41 words
A process as claimed in claim 1, in which there is present in the electrolyte an acid selected from boric, oxalic, malonic, maleic, tartaric, p-phenol sulfonic and sulfosalicylic acids in an amount of 0.1 to 10% by weight of the electrolyte.
Claim 6
Dependent Claim
28 words
A process as claimed in claim 1, in which the electrolyte is maintained at a temperature of 20° to 40°C while the voltage E 2 is being applied.
References Cited (Backward Citations)
US3773631A
Cited
US3759801A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-01-26 | 1979-07-28 | 1980-01-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-01-26 | 1983-07-28 | 1984-01-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-01-26 | 1987-07-28 | 1988-01-27 | $7700.00 | Window Closed / Lapsed |