Utilizing CeO2 modified graphene for enhancing tribological performance of lubricating oils

In this paper, nano-powders of CeO2 modified rGO(CeO2@rGO) with different mass ratios were prepared using a hydrothermal method with GO and Ce(NO₃)₃·6H₂O as the resources. Then, they were added into PAO5w-40 base oil to enhance its tribological properties. Experimental results showed that the synthesized CeO2@rGO has a laminar structure, with spherical CeO2 powders uniformly grafted onto the surface of graphene. The dispersion stability of the lubricating oil was enhanced by adding the CeO2@rGO composites, and it also increased with the proportion of CeO2 in the composite powders. When the CeO2:rGO composite nanopowders with a weight ratio of 3:1 were added, the dispersion stability of the lubricating oil showed the best performance. Its viscosity was slightly lower than that of the base oil, with a Zeta potential of 33.805 mV. Compared with the lubricating oil, the friction coefficients of the lubricating oil with the added nanocomposites were reduced by 31.9 %, and the wear depth and wear volume were reduced by 58.3 % and 83.3 %, respectively. Such excellent lubrication performance was mainly attributed to the effective barrier formed between the friction pairs of the nanocomposite-enhanced lubricating oil, and the uniformly dispersed nano-powders in the lubrication film, which played an effective rolling bearing effect between the friction pairs. Under the action of shear forces during wear processes, the rGO produced effective sliding movements among nanocomposite layers, which significantly reduced the friction coefficient and wear volume.