Influence of a succinimide dispersant on the tribological performance of MoS2 nanoparticles

In this study, the effect of a polyisobutenyl succinimide (PIB) dispersant on the tribological performances of MoS 2 nanoparticles used as lubricant additives in a PAO base oil was investigated. Friction tests were conducted in boundary lubrication regime, in a steel/steel sliding contact configuration, at room temperature and 100°C. The tribofilms formed on the rubbed surfaces were analyzed using X-ray Photoelectron Spectroscopy (XPS) and Transmission Electron Microscopy (TEM). The results show that the dispersant used in this work prevent the agglomeration/sedimentation of the nanoparticles and strongly improves their dispersion in the base oil. Its effect on the tribological performance of the nanoparticles was found to be temperature dependant. The best friction reducing properties were obtained at high temperature. It was also found that the dispersant strongly affects the tribofilm properties (chemical composition, thickness, MoS 2 flake length…) and that the best reducing friction properties were obtained when long and scarcely MoS 2 flakes aligned in the sliding directions compose the tribofilm.