Tribological properties of WS2/graphene nanocomposites as lubricating oil additives

Abstract

In this study, we prepared a new composite material of graphene (GP) anchored with WS₂ nanoparticles (WS₂/GP). The lubricating potential of the as-prepared nanocomposites as oil additives was investigated with sliding steel-on-steel contact using a UMT-2 ball-on-plate tribotester. The oil dispersed with WS₂/GP displays remarkable lubricating performance; the friction coefficient and the wear rate were reduced by 70.2% and 65.8%, respectively, when 0.02–0.04 wt% WS₂/GP was added to the base oil. Its friction-reducing and anti-wear abilities were also superior to those of oil containing a single nanomaterial of GP or WS₂ nanoparticles (nano-WS₂) and oil dispersed with a physical mixture of nano-WS₂ and GP. WS₂/GP may deposit on the wear surfaces and form a protective film, which improves the contact state of the sliding interfaces. Moreover, a synergistic lubricating action between the GP and nano-WS₂ in the WS₂/GP nanocomposites was revealed. We suggest that these two nano-additives cooperatively work, which enhances the adsorption of GP layers and deposition of nano-WS₂, thereby resulting in an improved protective and repairing effect.