The excellent anti-wear and friction reduction properties of silica nanoparticles as ceramic water lubrication additives

Abstract Water lubricated ceramics have gained extensive attention in recent years due to superior mechanical and environmental-friendly properties. Meanwhile nanoparticles have been found to greatly enhance the tribological properties when added into lubricants and silica nanoparticles being a distinctive example is widely studied. In this paper, 100 nm silica nanoparticles were synthesized, modified with functional groups and dispersed into water-based lubricant for silicon nitride ceramics friction pairs. The tribological properties for a series of different concentration lubricants were tested. It was experimentally proven that silica nanoparticles can greatly reduce both wear and friction. Moreover, amino modified nanoparticles showed the best lubrication performance and the optimal additive concentration was 5 wt%, COF dropping by 38.3% and running-in time by 49.4% when compared with the same concentration unmodified silica nanoparticles solution. Based on the analyses of SEM and EDS, there were two dominant lubrication mechanisms: filling and film-forming effect.