Tribological Investigation of Base Oil Supplemented with Zirconia Nanoparticles at Various Operating Temperatures

This study examines oil samples with zirconium dioxide (ZrO2) nanoparticles in Group III base oil at different temperatures, revealing the effects of temperature and concentration on the tribological system. The samples contain 0.1% and 1% ZrO2 nanoparticles, tested at 40–120 °C. The friction results showed that the nanoparticles increase the friction absolute integral values at all tested temperatures; however, static friction can be improved by 3–13%. The study demonstrates the wear-resistant effect of ZrO2 nanoparticles. Significant wear reduction can be achieved even at low concentrations; wear volume can be reduced by 21–87% depending on the nanoparticle concentration and operating temperature. Scanning electron microscopy with EDX helped to identify wear types, the processes occurring on the surfaces, and the percentage of nanoparticles on the surface.