Abstract: A process for treating the surface of aluminum or aluminum alloy comprising the steps of contacting aluminum or aluminum alloy with hot water or steam to form an aluminum oxide layer thereon and conducting electrolysis using the resulting aluminum or aluminum alloy as an anode by applying direct current in an aqueous solution consisting essentially of a water-soluble salt of at least one oxyacid selected from the group consisting of silicic acid, phosphoric acid, molybdic acid, vanadic acid, permanganic acid, stannic acid and tungstic acid.

Abstract: A coating composition for electrodeposition contains water soluble or water dispersible resin and at least one water soluble oxy-acid salt being selected from the group consisting of stannates, molybdates, tungstates, vanadates and borates, or a mixture of said water soluble oxy-acid salts. The coating formed from said composition on a metallic surface by electrodeposition is excellent in the adhesiveness and anti-corrosive property.

Abstract: In coating aluminum or aluminum alloy by contacting the aluminum or aluminum alloy with hot water or steam to form an aluminum oxide layer on its surface and thereafter electrophoretically coating the aluminum or aluminum alloy with an electrophoretic coating composition to form a resin layer, a process which is characterized in that said electrophoretic coating composition contains at least one water-soluble salt of an oxyacid selected from the group consisting of silicic acid, boric acid, phosphoric acid, vanadic acid, tungstic acid, permanganic acid, molybdic acid and stannic acid.

Abstract: A process for coating an aluminum or aluminum alloy comprising the steps of subjecting aluminum or aluminum alloy to boehmite treatment or chemical conversion treatment, conducting electrolysis using the resulting aluminum or aluminum alloy as an electrode in an aqueous solution of a water-soluble salt of at least one oxyacid, and thereafter coating electrophoretically the aluminum or aluminum alloy with an aqueous organic coating composition containing a binder resin and a water-soluble salt of at least one oxyacid to form a resin layer, said oxyacid contained in the aqueous solution and aqueous organic coating composition being at least one oxyacid selected from the group consisting of silicic acid, boric acid, phosphoric acid, molybdic acid, vanadic acid, permanganic acid, stannic acid and tungstic acid.

Abstract: A coating process for articles made of aluminum or aluminum alloy to form a composite coating which is excellent in adherent and anti-corrosive properties, in which the articles are treated in an aqueous solution of water-soluble oxyacid salts selected from the group consisting of silicates, borates, phosphates, chromates, molybdates, vanadates and permanganates with applying electric current to form a conversion coating layer on the aluminum surface, and are further treated with a water-soluble or water-dispersible coating composition to form a finish coat on the conversion coating layer particularly by dipping or electrodeposition.

Abstract: A process for coating an aluminum or aluminum alloy comprising the steps of subjecting the aluminum or aluminum alloy to boehmite treatment or chemical conversion treatment, anodizing the resulting aluminum or aluminum alloy in an aqueous solution of a water-soluble salt of at least one oxyacid, and thereafter coating the aluminum or aluminum alloy with an organic coating composition to form a resin layer, said oxyacid being at least one oxyacid selected from the group consisting of silicic acid, boric acid, phosphoric acid, molybdic acid, vanadic acid, permanganic acid, stannic acid and tungstic acid.