Patent ID: 6346295
Filing Date: 2002-02-12
Classification: C23C

Abstract:
A process for the alkaline passivation of a metal surface selected from the group consistng of galvanizd steel, alloy-galvanized steel and aluminum comprising:a) forming an alkaline aqueous solution comprising: 1) 0.1 to 1 gl of magnesium ions; 2) 0.1 to 1 g/l of iron (III) ions; and 3) 0.5 to 5 g/l amino or hydroxycarboxylate ions; 4) 0.001 to 10 g/l of a member selected from the group consisting of acrylic acid ions, methacrylic acid ions, oligomers comprising acrylic acid residues, oligomers comprising methacrylic acid residues and mixtures thereof; wherein said aqueous solution has a free alkalinity in the range of 5 to 20 points and a total alkalinity in the range of 7 to 30 points; and b) containing the metal surface with the alkaline aqueous solution.