Investigation on the Tribological Properties of POM Modified by Nano-PTFE

The tribological properties of polyoxymethylene (POM) modified by nano-polytetrafluorethylene (nano-PTFE) were investigated by a block-on-ring wear tester. For comparison, modified POM with micro-polytetrafluoroethylene (micro-PTFE) was also studied. The modified POM with a much lower concentration of nano-PTFE showed the similar tribological properties compared with POM modified by micro-PTFE. The friction coefficient decreased with the increase of nano-PTFE, while the wear rate showed the lowest value when the concentration of nano-PTFE was 2%. Scanning electron microscope (SEM) micrographs revealed that transfer films played an important role in the friction process. The transfer films decreased and stabilized the friction coefficient. Comparing to POM/2% nano-PTFE, when the concentration of nano-PTFE reached 4%, the mechanical properties decreased significantly, possibly due to poor dispersion of nano-PTFE.