Influence of interlayers on corrosion resistance of ion-plated Mg thin films

It is well known that the film formed by PVD process has different characteristics depending on the process conditions. In this experiment, therefore, the corrosion characteristic of Mg film prepared by PVD method onto electroplated Zn, Al and Sn steel substrates at different Ar gas pressure conditions is studied. From the experimental results, the corrosion resistance of Mg film is obviously correlated with the morphology of film and a formation of galvanic couple with interlayer. The film of granular structure which deposited in condition of high gas pressure has certainly good corrosion resistance. Especially Mg film on Zn interlayer, a sacrificial anode protection to substrate is continuously sustained by relatively low galvanic current in galvanic couple between deposited Mg film and Zn interlayer during immersion in 3% NaCl solution.