Investigation of the tribological behavior of oil-soluble Cu nanoparticles as additive in liquid paraffin

Cu nanoparticles coated with dialkyldithiophosphate (Cu-DDP) were synthesized in-situ by redox method. The size and structure of the nanoparticles were characterized by TEM and ED. The tribological behaviors of Cu-DDP as additive in liquid paraffin were evaluated and compared with that of zinc dialkyldithiophosphate (ZDDP) on a four-ball machine. The results show that Cu nanoparticles possesses excellent load carrying capacity and good antiwear property, which are better than that of ZDDP. The lubricating mechanism of Cu nanoparticles was discussed, based on the XPS and EPMA analytical results.