Influence of silica nanoparticles on running-in performance of aqueous lubricated Si3N4 ceramics

Abstract Water lubricated ceramics can achieve superlubricity following the running-in period. Nanoparticle lubricant additive is proven to significantly reduce the running-in period. However, the comprehension of the nanoparticle running-in period reduction mechanism is limited. In this paper, different types of tribology tests for Si3N4 ceramics lubricated via aqueous lubricant with nanoparticles are designed. Lubricant additives are added at different time points to ensure the effect silicon nanoparticles on running-in duration. Ceramic wear surfaces at various experimental time points are examined by the scanning electron microscope and optical microscope. The changing trend of COF during running-in period is studied. Mechanism of the surface film generation is proposed. It is found that rapid surface film generation is the essential for reducing the running-in period. Nanoparticles are depositing on the wear surface and gradually forming homogenous surface film. Ultimately, the surface film covers the wear surface and achieves dynamic balance.