Silver/Graphene Nanocomposite as an Additive for Aqueous Lubrication

From the perspective of economic and environmental protection, water-based lubrication is one of the most promising technologies. However, the weak lubricity of water impedes its wide application in the ceramic bearing industry. Herein, a silver/graphene nanocomposite (SGN), as an additive with good dispersity in water, was synthesized through electrostatic adsorption and in situ reduction after preparing the sulfonated graphene oxide. It was found that the tribological performance of ceramic components was significantly improved with the addition of the SGN in water. The experimental results indicated that a 0.2 wt % SGN aqueous solution contributed toward 52.2 and 54.2% of improvement in friction reduction and wear resistance, respectively, at 150 rpm and 3 N. In addition, frictional tests at a long duration of 3600 s were carried out to investigate the lubrication of the mechanism. The worn surface analysis demonstrated that the collapsed Ag nanoparticles adhered to the rubbing surface to produce a protective coating and repair worn surfaces. The superior lubricity of the SGN might be attributed to the synergistic effects of rolling of Ag nanoparticles and interlayer shearing of graphene, which worked at interfaces between components during sliding.