Tribological behavior of oleic acid coated PbO nanoparticles as additive in liquid paraffin

A four-ball machine was used to investigate the tribological behavior of oleic acid coated PbO nanoparticles as additive in liquid paraffin. A comparative investigation was also carried out on the same tester. The worn surfaces of the steel balls were analyzed by X-ray photoelectron spectroscopy, scanning electron microscopy and energy dispersion spectroscopy. It is found that the oleic acid coated PbO nanoparticles can improve the friction-reducing and antiwear ability of liquid paraffin. It shows better friction-reducing and antiwear performance than lead oleate as well. A boundary film mainly composed of PbO is formed on the steel ball surface under the lubrication of liquid paraffin containing oleic acid coated PbO nanoparticles. This contributes to improve the friction-reducing and antiwear behavior of the base stock.