TREATMENT BEFORE COATING OF STAINLESS STEEL

PURPOSE:To form the film excellent in adhesion with an org. material coating layer by impressing a square wave electric potential on the stainless steel immersed in an electrolyte bath. CONSTITUTION:Cu-containing stainless steel is immersed in the acidic electrolyte bath such as a sulfric acid bath, and the square wave electric potential vibrating from the electric potential range EL which is lower than the passivation electric potential E1 of Cr to the higher electric potential range EH which is the potential range from the natural electric potential E2 of Fe to passivation completed electric potential E3 of Fe, is impressed repeatedly. In this way, the metallic ion eluted from the stainless steel by electrolysis in the higher electric potential range EH is deposited on the surface of the stainless steel by electrolysis in the lower electric potential range EL, thus a film is formed. In the process of the elution-deposition, the Cu included in the stainless steel is condensed in the film, and the surface layer high in affinity with gum, resin, coating etc., is obtained.