Patent ID: 9334577
Filing Date: 2016-05-10
CPC Classification: C23C,C25D

Claim Text:
1. A method for applying a multifunctional coating to the surface of an untreated workpiece made of aluminium or of an aluminium alloy, wherein the method comprises the following: a) treating a surface of the untreated workpiece made of aluminium or of an aluminium alloy with an acidic solution which contains rare-earth metal ions, to produce a treated workpiece with a first oxide layer thereon, wherein the acidic solution has a pH of <1 and the treating of step a) occurs at a processing temperature of 50° C. to 80° C; and b) anodising the treated workpiece to produce a second oxide layer, the treated workpiece serving as anode of an electrical cell in the presence of an aqueous sulphuric acid-containing solution and the first oxide layer produced in step a) being retained, wherein the anodising of step b) occurs at a processing temperature of 15 to 35° C.