The friction and wear properties of polytetrafluoroethylene filled with ultrafine diamond

Abstract

The friction and wear properties of polytetrafluoroethylene (PTFE) filled with ultrafine diamond (UFD) were studied in detail on a block-on-ring wear tester under dry sliding conditions. Transmission electron microscope (TEM) was used to research microstructure of the purchased UFD and the purified UFD. Scanning electron microscope (SEM) and differential scanning calorimetry (DSC) were utilized to investigate material microstructures and examine modes of failure. Experimental results showed that there was no significant change in coefficient of friction, but the wear rate of the PTFE composite was orders of magnitude less than that of pure PTFE with increasing purified UFD content. Analysis of SEM indicated UFD in PTFE matrix had effects of loading-carry and increasing formation of transfer films on the steel counterpart surface as well as inhabiting generation of bigger debris. Furthermore, DSC disclosed that the PTFE composite with higher heat absorption capacity exhibited improved wear resistance. Wear mechanism was probably that UFD particles had a function of rolling bearing in frictional interface, and resulted in change of PTFE frictional form from single macromolecular sliding friction to a mixed form of sliding and rolling friction, accordingly UFD in PTFE could obviously decrease wear of pure PTFE.