Preparation and tribological properties of novel boehmite/graphene oxide nano-hybrid

Novel boehmite/graphene oxide nano-hybrid (GO–GPTS–AlOOH) was prepared through a simple covalent bond method, which was subsequently explored as lubricant additive. For this purpose, the 3-glycidoxypropyl-trimethoxysilane (GPTS) was first chemically grafted on nano-boehmite (AlOOH) to fabricate the modified boehmite (GPTS–AlOOH). Then the GPTS–AlOOH was anchored on graphene oxide (GO) nanosheets to prepare GO–GPTS–AlOOH nano-hybrid through a coupled reaction. The structure, composition and morphology of GO–GPTS–AlOOH was characterized by FT-IR, XRD, TG/DTG, SEM and TEM, revealing that nano-boehmite was uniformly coated on GO surface. More importantly, tribological properties of GO–GPTS–AlOOH as lubricating oil additive were investigated using a ball-on-disc testing machine and a four-ball machine. It was found that the friction reduction and anti-wear ability of lubricant oil containing GO–GPTS–AlOOH hybrid was highly improved compared to bare base oil (VHVI8). Specifically, friction coefficient (COF), wear scar diameter (WSD) and wear rate were reduced by 14%, 28% and 73%, respectively. The enhancement can be attributed to the synergistic effect of the nanobearing mechanism and ultimate strengthen of graphene sheets between the frictional interfaces.