Simultaneous plasma-electrolytic anodic oxidation (PAO) of Al–Mg compounds

A process for the simultaneous plasma-electrolytic anodic oxidation (PAO) of a compound consisting of an Al (AlMgSi1) and Mg (AZ31) alloy is introduced. Using this process, an almost uniformly thick, compact oxide coating on both compound partners can be produced provided that the narrow window of this process is determined and kept. The most important parameters for the simultaneous plasma anodizing are the composition and conductivity of the used electrolyte, the current density and the process time. A short-time process using high current densities has been found suitable. This process is a promising procedure for the protection of Al- and Mg-based compound surfaces.