Effect of MoS₂ on the tribological properties of in situ Fe ₃Al-20 wt% Al₂O₃-4 wt% Cr composites

Fe₃Al-20 wt% Al₂O₃-4 wt% Cr composites containing 0, 5 and 8 wt% MoS₂ were subjected to mechanical alloyinginducing self-propagating high temperature synthesis with subsequent hot-pressing sintering. Microstructures of the composites were studied by X-ray diffraction, scanning electron microscopy and energy dispersive spectrum analysis. Then the relative density, room temperature hardness and dry sliding wear behavior of the sintered composites at 25 °C, 500 °C and 800 °C were tested and analyzed. The results showed that composites with different amounts of added MoS₂ had good microstructure with high relative density and high hardness. The MoS₂ decomposes during sintering with the formation of Fe₃Mo₃C and Cr₂S₃. Cr₂S₃ formed from the decomposition process may form a lubricating film that can decrease the friction coefficient. At 800 °C, Fe₃Al-20 wt% Al₂O₃-4 wt% Cr with 8 wt% added MoS₂ exhibited a friction coefficient that was nearly 50% lower than that for the sample with no MoS₂ addition. Addition of 8 wt% MoS ₂ transformed the wear mechanism from adhesive wear to microploughing.