Dependence of high temperature tribological performance of MoS2-based composites on type of oxides

As a solid lubricating material with excellent anti-friction and anti-wear performance, MoS₂ is prone to oxidation in high temperature and atmospheric environment, which leads to the deterioration of lubricating performance and the decrease of service life. The addition of nano-particle oxides can improve the high-temperature lubricating performance of MoS₂-based solid lubricating materials to some extent, but the effects of different nanoparticles oxides under the same test condition is still unclear. The effects of nano-particles oxides (TiO₂, Cr₂O₃, Al₂O₃ and ZrO₂) on the tribological performance of MoS₂-based composites at 450 °C were compared. It was shown that MoS₂-TiO₂ exhibited the best high temperature tribological properties, and its average friction coefficient was about 0.26, which was about 26 % and 10 % lower than that of 718 substrate and MoS₂, respectively. Here we attempted to propose a new concept of correlative potential to explain the lubricating difference of binary oxides under high temperature. The good tribological performance of MoS₂-TiO₂ at high temperature was attributed to the low correlative potential of TiO₂ nanoparticles and the dense tribo-oxide layer formed at the friction interface that reduce the shearing of the rubbing interface. The research results can provide reference for the selection and design of MoS₂-based composites, and also enrich the theory of high temperature tribology.