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

In this study, four ZrN_xO_y 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 O₂ 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 H³/E² values showed a decreasing trend with the increasing O₂, 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 ZrN_xO_y 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 ZrN_xO_y 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.