Al2O3/Mo composite and its tribological behavior against AISI201 stainless steel at elevated temperatures

Al2O3-reinforced molybdenum (Mo) composites were successfully prepared by powder metallurgy to improve the wear resistance of Mo components at high temperature. The reinforced Al2O3 particles are uniformly distributed in the Mo matrix; thus, the Al2O3/Mo composite is harder than monolithic Mo. The friction coefficients of both monolithic Mo and the Al2O3/Mo composite decrease by 37% and 42%, respectively, at 700 °C compared with those at room temperature (self-lubricating phenomenon). This phenomenon is attributed to the formation of very soft MoO3 and FeMoO4 metal oxides on the friction surface at high temperature. The Al2O3/Mo composite has better wear resistance than monolithic Mo at both room temperature and at 700 °C. The notable resistance of the composite particularly at 700 °C can be attributed to its increased hardness and the soft tribofilm forming on the worn surface.