Influence of duty cycle on microstructure, tribological and corrosion behaviors of a-C/a-C:Ti multilayer films

• a-C/a-C:Ti multilayer films with various duty cycles were prepared by magnetron sputtering.
• Hardness of the as-deposited films increases with duty cycle.
• The as-deposited film with duty cycle of 45% has high adhesion strength of about 80 N.
• The as-deposited films show good tribological behaviors in ambient air and Hank's solution.
• a-C/a-C:Ti multilayer films enhance the anticorrosion properties of Ti6Al4V alloy.

a-C/a-C:Ti multilayer films were deposited on medical Ti6Al4V alloy using a closed field unbalanced magnetron sputtering system with various substrate bias duty cycle. The tribological and corrosion behaviors of the multilayer films in Hank's solution were evaluated by a ball-on-disk tribometer and an electrochemical workshop. The duty cycle has a significant effect on the bonding structure, and mechanical and tribological properties of the films. The polarization resistance of the films on Ti alloy is approximately ten times more than that of Ti6Al4V which indicates that higher corrosion resistance can be achieved in Hank's solution at 37 °C. However, the polarization resistance and corrosion current do not change so much with the variation of duty cycle, implying that its influence on corrosion behavior of these a-C/a-C:Ti multilayer films is not so obvious.