High temperature tribological behaviour of Al/Al₂O₃ composite coating on γ-TiAl

To improve the high temperature wear resistance of Ti–46·5Al–1Cr–1·5V, an Al/Al₂O₃ composite ceramic coating was prepared on it by radio frequency sputtering. In this paper, microstructure, elements distribution, phase identification of the Al/Al₂O₃ composite coating were investigated. Also, its nanohardness and elastic modulus were examined. High temperature dry sliding wear behaviour at 300°C was analysed in details. The results indicated that the homogeneous and dense composite coating was about 20 μm thick. Additionally, the composite coating possessed higher H/E and H³/E² ratios than those of substrate. Compared to the substrate, the Al/Al₂O₃ composite coating recorded a lower friction coefficient and the volume loss of Al/Al₂O₃ coating was only 1/3 of the bare substrate under dry sliding conditions at 300°C. All the results demonstrated that the Al/Al₂O₃ coating has effectively improved the wear resistance of Ti–46·5Al–1Cr–1·5V at 300°C.