Mechanical, tribological, corrosion and tribocorrosion properties of ZrN_xO_y coatings on Ti-45Nb alloys by multi-arc ion plating

In this study, four ZrNxOy coatings were deposited on the surface of Ti-45Nb alloy by multi-arc ion plating technology at different N/O ratios. The effects of oxygen content on the mechanical properties, wear resistance, electrochemical corrosion and tribocorrosion properties of the coatings were investigated separately. As the increasing of O-2 ratio, the hardness value decreases from 30.2 to 9.7 GPa; the Young's modulus values decrease from 322.1 to 172.2 GPa. The H/E and H-3/E-2 values showed a decreasing trend with the increasing O-2, which indicates a gradual decrease in the load-bearing capacity of the coatings. The critical load of these coatings in scratch test ranges from 12 N, 7.2 N, 5 N to 3N. In the friction test, both the TiNb alloy and coating exhibited predominantly abrasive and adhesive wear. The relatively low wear rate of the ZrN coating demonstrated its excellent wear resistance; however, the wear-resisting property of the ZrNxOy coating gradually decreases as the oxygen content increases, and ZrO2 coating showed the poorest wear resistance. On the contrary, the higher the oxygen content, the better the electrochemical corrosion resistance, and ZrO2 coating showed the excellent corrosion resistance. The results of tribocorrosion test show that the ZrNxOy coating has better wear resistance in simulated body fluid solution compared to Ti-Nb alloys. The experimental results and design concepts of the paper can provide a better understanding of the preparation of medical titanium alloy surface functional coatings with good comprehensive performance.