Physical, Chemical, and Atomic Interactions During Combined Vapor Deposition and Sputtering on ZK60 Mg alloy
Abstract - Application of PVD for the development of thin coatings on magnesium alloy ZK60 for protection against corrosion was studied. Two methods, magnetron sputtering and ion-vapour deposition, in inert and reactive environments were used and the relationship between process, microstructure, and morphology were studied. The dual-mode system was demonstrated to be able to produce high quality, thin and homogenous coatings in Mg alloy substrate. The best methods for pre-processing, both ex- and in-situ of the deposition chamber were investigated and their impact on the coatings were assessed. It was found that improper cleaning prior to mounting the sample in the deposition chamber can lead to significant damage and loss of surface quality in the part upon ion bombardment and plasma flow due the interaction of left-over oxides on the surface with the plasma. Poisoning of the magnetron must be minimized by isolating it as much as possible from the nitrogen. The voltage across the magnetron drops significantly if that is not avoided and the magnetic field needed to generate the plasma shield for sputtering cannot be maintained. This system was successfully used to deposit inter metallic, conglomerate and nitride coatings. Micro structural investigation reveals that dense coatings with fine microstructures and uniform thickness were obtained in all three modes.
Keywords - Magnesium alloys, Coatings, PVD method, Corrosion resistance.