Influence of sulfides on the tribological properties of composites produced by pulse electric current sintering

Self-lubricating Al₂O₃-15wt% ZrO₂ composites with sulfides, such as molybdenum disulfide (MoS₂) and tungsten disulfide (WS₂) serving as solid lubricants, were fabricated by using the pulse electric current sintering (PECS) technique. The coefficient of friction (COF) of the Al₂O₃-15wt% ZrO₂ composite without/with sulfides was in the range of 0.37–0.48 and 0.27–0.49, respectively. As the amount of sulfides increased, the COF and the wear rate decreased. The reduction in COF and wear rate of the sulfide-containing composite is caused by a reduction in shear stresses between the specimen and the tribological medium due to the formation of a lubricating film resulting from the lamellar structure of sulfides located on the worn surface.