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US 5,451,271 AGranted
Conversion treatment method and composition for aluminum and aluminum alloys
AssigneeHenkel Corporation
InventorsMasayuki Yoshida, Kazuya Nakada
Life of this patent
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AssigneeHenkel Corporation
InventorsMasayuki Yoshida, Kazuya Nakada
Estimating the term…
The paint adhesion and corrosion resistance of surfaces of aluminum and its alloys, particularly when using a paint based on poly{vinyl chloride}, is improved by using a conversion coating solution having a pH in the range from 1.0 to 3.0 and consisting essentially of water and: (A) an amount of phosphate ions that is stoichiometrically equivalent to at least 5.0 g/L of phosphoric acid; (B) at least 1.0 g/L of hexavalent chromium; (C) at least 0.1 g/L of fluoride ions; and (D) a complex fluoride ion component selected from the group consisting of: (i) at least 4.0 g/L of fluosilicate ions, (ii) at least 0.5 g/L of fluoborate ions, (iii) at least 2.0 g/L of fluozirconate ions, and (iv) at least 2.0 g/L of fluotitanate ions.
An aqueous conversion coating solution that has a pH value from 1.0 to 3.0 and consists essentially of:
A process for treating a surface of aluminum or an aluminum alloy, said process comprising steps of forming a conversion coating on said surface and subsequently overcoating the conversion coated surface with an organic protective coating, wherein the conversion coating on said surface is formed by contacting said surface with an aqueous solution having a pH value from 1.0 to 3.0 and consisting essentially of:
Dependencies are inferred from the claim text.