Tribological Behaviors of Oxynitride Coating on TC4 Alloy Prepared by Double Glow Technology

Abstract

The oxynitride coating was fabricated on the surface of Ti6Al4V alloy via double glow plasma alloy technology to enhance the wear resistance. The protective coating is dense and homogeneous and has a multilayer structure (outermost oxygen-rich layer, middle nitrogen-rich layer, innermost nitrogen diffusion layer). The acoustic emission curve suggests that the critical load is 53.1 N, the bonding strength between oxynitride coating and substrate is adequate to the application due to the diffusion layer. The oxynitride coating has a maximum hardness about 1020 HV, which is significant harder than Ti6Al4V alloy (370 HV). Tribological behaviors of oxynitride coating were investigated at three loads. The results indicated that the friction coefficient of oxynitride coating is lower than that of substrate at the same conditions. The wear mechanism of oxynitride coating is mainly fatigue wear, which converts to adhesive wear and fatigue wear with increasing load. The protective layer can decrease the actual contact areas obviously during the wear tests, which attributed to the higher hardness and stability of oxynitride layer.

Keywords

• double glow plasma technology
• oxynitride coating
• tic4 alloy
• tribological behavior
• diffusion