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

Abstract Al 2 O 3 -reinforced molybdenum (Mo) composites were successfully prepared by powder metallurgy to improve the wear resistance of Mo components at high temperature. The reinforced Al 2 O 3 particles are uniformly distributed in the Mo matrix; thus, the Al 2 O 3 /Mo composite is harder than monolithic Mo. The friction coefficients of both monolithic Mo and the Al 2 O 3 /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 MoO 3 and FeMoO 4 metal oxides on the friction surface at high temperature. The Al 2 O 3 /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.