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US 4,060,462 AGranted
Color anodizing of aluminum
AssigneeAluminum Company of America
InventorWilliam P. Kampert
Life of this patent
Estimating the term…
Abstract
A process for producing a colored coating on aluminum comprises anodizing the aluminum at a voltage in the range of 6 to 24 volts in a sulfuric acid electrolyte and thereafter reducing the voltage to not greater than 3 volts while further anodizing the aluminum in the aforementioned electrolyte thereby producing the colored coating.
Claims8
A process capable of producing a colored anodic coating on an aluminum alloy substrate comprising:
- a. anodizing said aluminum in a sulfuric acid electrolyte at a direct current voltage in the range of 6 to 24 volts to provide a conventional, substantially colorless coating thereon;
- b. thereafter, reducing the voltage to a direct current voltage in the range of 0.5 to 3 volts while continuing to anodize said aluminum in the electrolyte;
- and
- c. anodizing said aluminum alloy substrate at said voltage in the range of 0.5 to 3 volts for a period of time not greater than 15 minutes to produce the colored anodic coating by increasing the thickness of a barrier zone located intermediate the conventional coating and the aluminum alloy substrate.
1 more element
A process capable of producing a colored anodic coating on aluminum alloy substrate, the process comprising:
- a. providing an aluminum-magnesium-silicon alloy substrate in a T52 temper;
- b. anodizing the aluminum substrate in a solution containing 12 to 18 wt.% sulfuric acid, the remainder essentially water, said anodizing being performed at a direct current voltage in the range of 12 to 20 volts and a temperature in the range of 60.degree. to 95.degree. F to provide a conventional, substantially colorless coating thereon;
- c. thereafter, reducing said voltage to a direct current voltage in the range of 1 to 2.5 volts while continuing to anodize said aluminum alloy substrate;
- and
- d. anodizing said aluminum article at said voltage in the range of 1 to 2.5 volts for a period in the range of 4 to 12 minutes to produce the colored anodic coating by increasing the thickness of a barrier zone located intermediate the conventional coating and the aluminum alloy substrate.
2 more elements
Dependencies are inferred from the claim text.