Study on the Interaction Mechanism Between Oil Soluble Lanthanum Borate Nanosheets and Traditional Lubricating Additive in Different Base Oil

Abstract In this study, oleic acid-modified lanthanum borate nanofluids (OA-LBNs) were compounded with traditional additives such as molybdenum dithiocarbamate (MoDTC), molybdenum dialkyl dithiophosphate (MoDDP), and zinc dialkyldithiophosphate (ZDDP) in different proportions in poly (alpha olefin) (PAO4) and diisooctyl sebacate (DIOS) base oil, respectively. The friction-reducing and antiwear properties of the samples were investigated using a four-ball friction tester. The surface morphology, elemental composition, and tribofilm structure of the wear scars were analyzed using a scanning electron microscope, a 3D profilometer, and an X-ray photoelectron spectrometer. The interaction mechanism between OA-LBNs nanoadditives and traditional lubricant additives was studied. It was found that there is an antagonistic effect between OA-LBNs and MoDTC/MoDDP/ZDDP in weakly polar PAO4 base oil. When OA-LBN nanoadditive is combined with traditional lubricating additives, MoDTC/MoDDP/ZDDP in PAO4, competitive adsorption occurs between the additives, weakening each other's content on the friction surface, resulting in weakened tribological properties. On the contrary, OA-LBNs have a synergistic effect with MoDTC/MoDDP/ZDDP in polar DIOS base oil. When OA-LBNs are used in combination with traditional lubricant additives such as MoDTC, MoDDP, and ZDDP, respectively, the traditional additives promote the competitive adsorption between OA-LBNs nanoadditives and DIOS base oil, thereby exhibiting enhanced tribological properties.