Sliding tribological properties of nano-sized ceramic particles as oil-based lubricant additives

The present research investigated the lubricating performance of ZnO, SiO2, and WS2 nanoparticles as oil additives applied on steel frictional pairs. The study consisted of two stages. In first stage, the lubricating properties of nanofluids were examined using the various nanoparticle concentrations. It was obtained that the 3wt% ZnO, 5wt% SiO2, and 3wt% WS2 nanofluids showed the best performance. In second stage, an orthogonal test matrix was designed to understand the influences of load, sliding frequency and surface roughness on the lubricating behavior of the nanofluids. It was found that the frequency and load had the most significant effects on the friction reduction and anti-wear properties of ZnO, SiO2, and WS2 nanofluids. By using scanning electron microscopy and energy dispersive X-ray spectroscopy for potential mechanisms. It was found that the nanoparticles could be physically embedded, and adhered to the worn areas to form tribo-films resulting in improved tribological performance.