METHODS FOR DEPOSITING FINISH COATINGS ON SUBSTRATES OF ANODISABLE METALS AND THE PRODUCTS THEREOF

摘要

New processes are disclosed for depositing metal coatings on substrates of anodisable metals, such as aluminium and its alloys, the coatings being applied directly on to a porous anodised layer that has been produced on the surface of the substrate. Pore-filling metal is first electrolytically deposited in the pores, the metal depositing initially on the bottom walls and the lower parts of the side walls; usually until the pores are from about 3 % to about 30 % filled. Metal deposition is then continued using an electroless process until the pores are filled to the desired extent, usually until a support coating has been applied over the entire anodised layer. Other metal coatings can then be applied over the support layer, either by electrolytic or electroless methods. Electroless coatings of considerable thickness (as much as 75 micrometres) can successfully be applied. The new products of such processes comprise a substrate of anodisable metal, having on a surface an anodised layer of thickness of about 0.5 to about 50 micrometres; the pores of the anodised layer have pore-filling metal electrolytically deposited therein, and pore-filling metal electroless deposited on the electrolytically deposited metal. The electroless metal may constitute the final layer or other layers may be deposited over it to give the final product. The interposed electrolytically deposited metal provides improved adhesion to the anodised material as compared to direct electroless deposited metal.