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US 5,472,522 AGranted
Making galvanized steel with excellent darkening resistance
AssigneeHenkel Corporation
InventorsJun Kawaguchi, Takao Ogino, Kensuke Mizuno
Life of this patent
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Abstract
To form a darkening-resistant chromate ram on the surface of a galvanized steel sheet, the surface of the galvanized steel shut is treated with a phosphate treatment solution before it is chromate-treated in such a way that zinc phosphate crystals will cover from 10-60% of the substrate surface.
Claims20
A method for imparting an excellent darkening resistance to a conventionally light colored and lustrous galvanized steel surface said method comprising:
- (1) treating a galvanized steel surface with a phosphate treatment solution so that zinc phosphate crystals are formed and deposited on only a fraction that is from 10 to 60% of the total area of said surface, and then
- (2) conventionally treating said surface with a chromating solution.
Dependencies are inferred from the claim text.