PVD coating and substrate pretreatment concepts for corrosion and wear protection of magnesium alloys

Magnesium is a prospective material to save weight and fuel due to its low density and its high specific strength. Nevertheless corrosion and wear resistance are weak so that the surface has to be protected. Previous studies of the authors pointed out the potential of TiMgAlN PVD-coatings for surface protection of Mg-alloys. Within the presented study, the chemical, structural and electrochemical properties of TiMgAlN based PVD coating materials were examined entirely. Therefore, coatings of different compositions were deposited onto the magnesium alloy AZ31 and on glass substrates. Glass substrates were used to examine the electrochemical properties of the coating materials without any substrate influence. The magnesium content in the coatings varied between 1 at.% and 60 at.%. Increasing Mg content in the coatings improves mechanical and electrochemical properties, thus making TiMgAlN prospective candidates to protect magnesium against wear and corrosion. Beyond this, addition of magnesium leads to a densification of the coating microstructure.