▎ 摘　　要

This research article investigates carefully the effect of different nanoparticles zinc oxide (ZnO), graphene, and combinations thereof in API base oil group Iota Iota (PBO-G Iota Iota). The morphology of zinc oxide and graphene nanomaterials are depicted by transmission electron microscopy. Sonication treatment and dispersion stability investigations are carried out after the preparation of nanoparticles with surfactant (oleic acid) and pure base oil group Iota Iota for certain concentrations. Oil formulations tested by using a four-ball machine to find out the coefficient of friction (COF), wear scar diameter (WSD), and specific wear rate (SWR) for each sample. Additionally, scarred balls are characterized by using field emission scanning electron microscopes (FE-SEM), energy-dispersive x-ray spectroscopy (EDX/EDS), elements mapping, Raman spectroscopy, and a three-dimensional surface texture analyzer to study the morphology of sliding balls after the tribological experiments and to confirm the presence of (zinc oxide+graphene) on the machined balls. Surface roughness measurements implemented for identifying surface finish of scarred balls. The experimental results and surface analyses showed that (0.4 wt.% ZnO+0.2 wt.% graphene) nanolubricant has outperformed behavior compared to base oil group Iota Iota due to the formation of tribofilm on the contacting surfaces during sliding motion.