Synergistic lubrication effects and tribological properties of graphene/oil-based lubricant systems

Graphene exhibits great potential as an additive to enhance the anti-wear and friction reduction capacity of moving mechanical components in a synergistic mechanism with the base oil. This paper considers the effect of different factors such as the number of base oil molecules, graphene content, normal load, sliding velocity and the presence of graphene. The synergistic mechanism of graphene and base oil is investigated by experiments and molecular dynamics (MD) simulations. The results show that the friction and wear reduction is due to the formation of the load-supporting graphene layers and sufficient base oil molecules between Fe slabs. Graphene can stably adsorb on the rubbing surfaces lubricated by the base oil, confirming that graphene can form a physical deposition film on rubbing surfaces. Low friction and wear can be achieved with higher sliding velocity and lower load. Furthermore, compared to the sliding velocity, the load significantly affects the mean square displacement of base oil and oleic acid molecules. These outcomes provide a better understanding of the tribological properties of graphene as a lubricant additive.