PURPOSE: To form a coating film excellent in weather resistance with excellent adhesion by forming an anodically oxidized film on the surface of an Al-based metal member, electrolytically treating the film in a soln. contg. phosphoric acid and coating the film with a coating material.
CONSTITUTION: The surface of an Al or Al alloy member is washed, the member is immersed in an acidic aq. soln. contg. sulfuric acid and an anodically oxidized film is formed on the surface of the member by supplying electric current with the member as the anode. The member is then immersed in a phosphoric acid- based bath, pulled up and dried or the film is electrolytically trated in a phosphoric acid-based bath by supplying AC and the member is pulled up and dried. The film is finally coated with a coating material by spraying or dipping. A coated Al or Al alloy member having satisfactory adhesion of the anodically oxidized film to the coating material and excellent in weather resistance of the coated surface is produced.
ISHIDA SHINICHI
YAMADA KIKUO
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