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 mm3/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 wea