Method for formation of hydrophilic corrosion-resistant coating on the surface of metallic material

摘要

A hydrophilic corrosion-resistant coat is formed on the surface of a metallic material, e.g., aluminum and its alloys, by a method which comprises preparatorily cleaning the surface of the metallic material, applying on the cleaned surface of the metallic material an aqueous treating liquid produced by adding a water-soluble acrylic acid polymer and colloidal silica and effective amounts of a polyhydric alcohol and/or saccharide to an aqueous solution containing hexavalent chromium compound or trivalent and hexavalent chromium compounds, phosphoric acid, and a fluorine compound. The applied layer of the treating liquids is dried and baked, the baking being at a temperature in the range of 100 DEG to 250 DEG C.