Abstract:Graphene is often used in lubricating oil to improve the lubricating properties of the oil, but it is highly prone to agglomerate in the oil, and requires dispersants to inhibit agglomeration. The molecular behavior between graphene, dispersant and lubricant can reveal the dispersion mechanism, lubrication mechanism and synergistic effect. In this paper, we use span60, which is non-toxic to the environment, as a dispersant to study the lubricating property changes of graphene lubricant before and after adding span60 based on molecular dynamics, establish a structural model of silicon nitride - lubricant - bearing steel layer, analyze the content ratio of span60 to graphene, operating temperature, pressure and shear speed on the adsorption energy of lubricant film on the surface of friction substrate, shear stress and the thickness of the solid film formed, and verified experimentally. The synergistic effect of dispersant span60 and graphene in the lubricant improved the lubricating ability of the lubricant on the surface of Si3N4-GCr15 friction subsets. The best lubrication effect is achieved when the span60/graphene content ratio is 7:1; When the temperature is 373 K, the pressure is 102 MPa and the shear speed is 25 m?s-1, the lubricating performance of lubricating oil is the best. The addition of appropriate amount of span60 can effectively solve the agglomeration problem of graphene in lubricant, and the synergistic effect between graphene, dispersant and lubricant is influenced by temperature, pressure and speed.