Synergistic lubricating effect of graphene/ionic liquid composite material used as an additive

We prepared a graphene/ionic liquid(G/IL)composite material by the hybridization of G and an IL for use as a lubricating oil additive.The friction coefficient and wear volume of a base oil containing 0.04 wt%of the G/IL composite was reduced by 45%and 90%,respectively.Furthermore,the base oil containing the G/IL composite exhibited better lubricating properties than the base oil containing G,IL,or a mixture of IL and G at the same mass fraction.A synergistic lubrication mechanism was also revealed.The G/IL composite was adsorbed and deposited on the wear surface,forming a more ordered protective film and a unique tribochemical reaction film during rubbing.Therefore,the G/IL composite exhibited the synergistic lubricating effects of G and IL,which significantly improved the lubricating performance of the base oil.This study also suggested a way to limit the out-of-plane puckering of G at the macroscale.