Tribological performance and behaviour of CVD TiC/TiCN/TiN multilayer coating at elevated temperature

Abstract

TiC/TiCN/TiN multilayer coating was prepared on a high-speed tool steel W6Mo5Cr4V2 by chemical vapour deposition. The tribological performance and behaviour of the coating were investigated at an elevated temperature of 400–600°C. Results show that the friction coefficient of the coating first decreases from 0.39 to 0.08 and then increases from 0.08 to 0.23 with the increase in temperature, while the average wear rate increases continuously from 0.97 × 10⁻¹³ to 2.11 × 10⁻¹³ m³N⁻¹m⁻¹. The tribochemical product of Fe₂O₃ in the tribo-oxidative layer (TiO₂+ Fe₂O₃) could reduce the coating friction coefficient but enlarge the wear rate. As the Fe₂O₃ component increases, the consumption of the tribo-oxidative layer accelerates gradually and the coating wear mechanism transforms from the mild oxidative–abrasive–adhesive wear to severe oxidative–adhesive wear.