Carbon microspheres coated with graphene oxide nanosheets as oil-based additives for tribological applications

Abstract Carbon microspheres (CMS) coated with graphene oxide (GO) nanosheets particles were prepared and applied as an efficient lubricant additive for enhancing the tribological performances of lubricating oil in the boundary and mixed lubrication regimes. CMS was functionalized by 3-aminopropyltriethoxysilane (APTES) and then grafted with GO nanosheets suspension in the presence of catalysts. The tribological behaviors was studied using a tribometer under ball-on-disk (BOD) configurations. The hybrid lubricant containing 0.2-wt % graphene oxide/functionalized carbon microspheres (GO/f-CMS) particles exhibited a significant reduction in friction and wear (26 %–54 %) as compared with the reference engine oil (85W-90). Raman and SEM investigation of GO/f-CMS following the tribo-test proved their excellent mechanical and chemical stabilities. These performance improvements were attributed to the bearing and filling mechanisms of spherical particles and superior lubrication effect of GO nanosheets.