LAUSR

Abstract Low temperature thermal oxidation treatment is performed on the PVD (physical vapor deposition) hafnium-coated magnesium alloy. The results indicate that thin hafnium oxide film and new shallow grain boundaries were appeared on the coating surface. Surface oxidation and densification of the coating induced by the post treatment significantly decreased its susceptibility to corrosion. Moreover, the release of the residual stress produces a positive effect on suppressing the delaminating of the coating as magnesium is corroded. Consequently, the treated coating exhibits more positive corrosion potential, lower corrosion current density and higher polarization resistance than that of the untreated coating in Hanks’ solution. Salt spray test further reveals that the post-treated hafnium coating can provide a longer-term and more efficient protection for magnesium alloy.