High‐Temperature Tribological and Self‐Lubricating Behavior of Copper Oxide‐Doped Y‐ TZP Composite Sliding Against Alumina

The tribological behavior of 5 wt% copper oxide‐doped tetragonal zirconia polycrystal composite has been investigated while it slides against an alumina counterface under high temperature conditions. The effects of load (1, 2.5, and 5 N) and velocity (0.05 and 0.1 m/s) on the wear mechanism have been investigated. The results were compared with undoped zirconia at 595°C. A coefficient of friction ( COF ) of 0.35 and a specific wear rate less than 10 −6  mm 3 /Nm were obtained at 595°C when copper oxide was added to zirconia. Further, it has been observed that a self‐lubricating layer is formed at the interface. Scanning electron microscopy and X‐ray photoelectron spectroscopy have been used to investigate the formation of the self‐lubricating copper‐rich layer at the interface between the disk and counterface materials. The formation of a self‐lubricating layer, as well as the wear mechanisms at different operational conditions (load and velocity) are discussed. It appears that plastic deformation of copper‐rich phase at higher temperature is responsible for the decrease in friction and wear.