Friction and wear properties of Fe–Mo intermetallic compounds under oil lubrication

In this study several disc specimens of three different compositions of the Fe–Mo system were prepared by spark plasma sintering and annealing, and their friction and wear properties were investigated. It was found that, when ASTM 52100 steel balls were used as the paired materials, both the Fe–42 at% Mo and Mo disc specimens exhibited lower friction coefficients and lower wear rates than the Fe and cast iron disc specimens. It was also found that the spark plasma-sintered Fe–42 at% Mo disc specimens without any heat treatments exhibited lower friction coefficients than those annealed at 1323 K for 172.8 ks. According to the XPS analysis, iron oxides and iron sulfides were found on the worn surfaces of the Fe disc specimens that were slid against the ASTM 52100 steel balls, while molybdenum oxides such as MoO2, but not MoS2, were observed on the worn surfaces of the annealed Fe–42 at% Mo and Mo disc specimens that were slid against the steel balls.