The CeO2 nanoparticles were used as lubricating oil additives. The modified and surface-modified CeO2 nanoparticles exhibit good dispersion and stability in the lubricating oils. The constructure, morphology and mean diameter of nanoparticles of CeO2 were characterized and measured by transmission electron microscope(TEM) and X-ray diffraction (XRD). Tribological properties of the lubricating oils with CeO2 nanoparticles additives were evaluated on a four-ball tribotester. The worn surfaces were analysed by scanning electron microscope (SEM) and atomic force microscope (AFM). Experimental results indicate that, lubricating oils with CeO2 nanoparticles additives have excellent tribological properties of the friction reduction, wear resistance and higher load capability. By means of SEM and AFM investigations, the mechanism of excellent tribological performances of CeO2 nanoparticles additives was discussed, too.
