Wear performance of SiC/G coating at elevated temperatures

To improve the wear performance of SiC materials, a SiC/graphite (SiC/G) coating was prepared by CVD. Wear tests were conducted at elevated temperatures, and related microstructure and mechanical characteristics were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD) and micro-hardness tester. The results show that the SiC/G coating has excellent anti-wear performance with low friction coefficient at RT owing to the lubrication of graphite. Moreover, the friction coefficient of the SiC/G coating is lower than that of the uncoated SiC samples at all tested temperatures. As the temperature rose to 250 °C, the wear mechanism of SiC/G coating was shifted to severe adhesive wear, which resulted in an increase in friction coefficient. However, fracture and oxidation dominated the friction process of SiC/G at 500 °C, which caused an increase in wear volume. In addition, the formation of silica debris was conductive to the decrease of friction coefficient.