Tribological properties of nano-palygorskite/copper composites as lubricant additive to steel ball tripair

The nano-palygorskite/copper (nano-P/Cu)composites were prepared by liquid chemical reduction method and mechanical ball milling. The size and morphology of the nanoparticles were described by means of transmission electron microscopy(TEM) and particle size analyzer. The tribological properties of nano-P/Cu powders, in different mass fraction and component proportion, as 150 N base oil additive, were evaluated on a four ball friction and wear tester. The morphologies, element distributions and micromechanical properties of the worn surface were investigated by means of scanning electron microscopy(SEM) and energy dispersive spectrometry(EDS). The results indicate that almost all particle size of nano-P/Cu is less than 100 nm and the lubricant oil with nano-P/Cu additives is good in dispersion effect and stable. For steel ball tribopair, the tribological properties are best while the component mass ratio and content of nano-P/Cu composites is P:Cu=3:1 and 1wt% respectively. The wear scar diameter of sample lubricated with nano-P/Cu additive decreases 20.7% compared with the none additive. It can be deduced that an auto-restoration film composed of Mg, Al, Si and Cu elements forms on the worn surface to compensate the wear loss and make the surface smoother.