Patent ID: 8414711

Claim:
A method of surface treatment for aluminum or aluminum alloy, comprising the steps of: (A) immersing a workpiece to be treated, which comprises aluminum or an aluminum alloy on at least a surface thereof, in an alkaline aluminum oxide film-removing solution comprising a salt or oxide of a metal capable of substitution with aluminum and a solubilizer for ions of said metal, and forming a substituted metal layer of said metal, which is capable of substitution with aluminum and is contained in said removing solution, on a surface of the aluminum or aluminum alloy while removing an aluminum oxide film on said aluminum or aluminum alloy surface; (B) forming a substituted zinc film by zinc substitution treatment without removal of said substituted metal layer; (C) removing said substituted metal layer along with said substituted zinc film by means of a liquid having an oxidizing behavior; and (D) subjecting the resulting surface to zinc substitution treatment again to form a substituted zinc film thereon, wherein said metal is selected from the group consisting of manganese, iron, cobalt, nickel, tin, lead, copper, mercury, silver, platinum, gold and palladium.