TiN/CrN multilayer coating was deposited on AZ91D magnesium alloy by pulsed bias cathodic arc PVD process. Effects of the coating on wear and corrosion behaviours of magnesium alloy were investigated. The stick-tearing for adhesion evaluation, nanoindentation for hardness measurement, ball-on-disc testing for wear tests, and potentiodynamic polarization for corrosion tests were used. The results show that the friction coefficient is decreased and the wear resistance is improved remarkably by TiN/CrN multilayer coating on AZ91D magnesium alloy. The corrosion resistance of the alloy is increased at a certain degree.

The Mo surface modified layer on Ti6Al4V alloy was obtained by the plasma surface alloying technique. The structure and composition of the Mo modified Ti6Al4V alloy was investigated by X-ray diffraction (XRD) and glow discharge optical emission spectroscopy (GDOES). The Mo modified layer contains Mo coating on subsurface and diffusion layers between the subsurface and substrate. The X- ray diffraction analysis of the Mo modified Ti6Al4V alloy reveals that the outmost surface of the Mo modified Ti6Al4V alloy is composed of pure Mo. The electrochemical corrosion performance of the Mo modified Ti6Al4V alloy in 25°C Hank’s solution was investigated and compared with that of Ti6Al4V alloy. Results indicate that the self-corroding electric potential and the corrosion-rate of the Mo modified Ti6Al4V alloy are higher than that of Ti6Al4V alloy in 25°C Hank’s solution.