Synthesis and characterization of DDP-coated PbO nanoparticles

Di-n-hexadecyldithiophosphate (DDP) coated PbO nanoparticles have been chemically synthesized and characterized using infrared spectroscopy (IR), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA). The antiwear ability of the DDP-coated PbO nanoparticles as an additive in liquid paraffin was evaluated on a four-ball machine. Results show that DDP-coated PbO nanoparticles, with an average diameter of about 5 nm, are able to prevent water adsorption and are capable of being dispersed stably in organic solvents or mineral oil. Thermal stability of DDP coating on PbO nanoparticles is superior to that of pyridinium di-n-hexadecyldithiophosphate (PyDDP). Meanwhile, DDP-coated PbO nanoparticles can improve the antiwear ability of liquid paraffin even at an extremely low concentration.