Patent ID: 6846401

Claim:
A method for applying a metal layer onto at least one surface of an aluminium or aluminium alloy workpiece, comprising the steps of: pretreating said surface, wherein the pretreating step comprises the sequential steps of (a) non-electrolytic treatment by immersion of the workpiece in a single acid solution having a temperature of at most 100° C. and selected from the group consisting of a sulphuric acid or phosphoric acid solution, and (b) etching the workpiece using a voltage selected from the group consisting of an a.c. voltage and a pulse-current voltage, said voltage used in an acidic electrolyte capable of dissolving aluminium oxide and maintained at a temperature in the range of 30° C. to 100° C., under conditions such that on the surface of the workpiece no further oxide film is formed; and after said pretreating applying the metal layer to the pretreated at least one surface by plating.