Improvement of corrosion resistance and adhesion of coating layer for magnesium alloy coated with high purity magnesium

AZ31 magnesium alloy was coated with high purity magnesium by vapor deposition coating process at high temperature in order to improve the corrosion resistance. Interdiffusion of each element was observed at the interface during the deposition coating process. The high purity magnesium coating showed superior corrosion resistance in salt solution. Although corrosion resistance was improved dramatically by the vapor deposition coating process, there were a lot of voids and pin-holes at the interface and in the coating layer, respectively. Hot press and HIP processes were carried out to decrease the voids and pin-holes. They were disappeared completely by hot press and HIP processes, resulting in improvement of adhesion property. Moreover, corrosion resistance was also improved due to disappearance of voids and pin-holes. Besides, the high purity magnesium coating worked as sacrificial anode in the cross cut test, resulting in protecting the substrate.