Synergistic Mechanism of Two-Dimensional Layered G/MoS2/h-BN Ternary Composite Additives on the Tribological Properties of Lubricating Grease

Two-dimensional nanomaterials as grease additives have demonstrated significant research progress in the surface modification of mechanical friction pairs. However, single-component systems often struggle to meet composite lubrication demands under extreme conditions due to the antagonistic effect between antiwear and friction-reduction properties, limiting their engineering application. In this study, five greases were prepared using a multivariate compounding method. Among them, the ternary additive grease (GG2M2B), formulated with a mass ratio of 1:2:2 (1 wt % graphite, 2 wt % MoS₂, 2 wt % h-BN), exhibited superior stability and temperature resistance, showing a 6.5% increase in maximum operating temperature. The GG2M2B additive proved effective across wide load ranges (50-100 N) and at temperatures up to 200 °C. Analysis revealed that the additive reduced friction by leveraging its friction-induced physical properties. Specifically, it formed a stable tribo-film on the friction surfaces through a combination of friction-induced physical/chemical adsorption and tribochemical reactions. This resulted in a 49.8-52.7% reduction in the coefficient of friction and a 75-81.3% reduction in wear volume compared to the base grease. Further investigation indicated that the composite additive (G/MoS₂/h-BN) responded synergistically to high temperature, shear stress, and frictional heat. It underwent tribochemical reactions with iron (Fe) and oxygen (O) from the subsurface material, generating a series of compounds. These reactions significantly enhanced the friction performance and antiwear effectiveness. This study provides a novel component design strategy and theoretical foundation for developing adaptive composite grease additives.