The tribological behavior of nanometer and micrometer TiO2 particle-filled polytetrafluoroethylene/polyimide

The friction and wear properties of micrometer and nanometer TiO2 particle-filled polytetrafluoroethylene (PTFE)/polyimide (PI) composites were studied in this paper. The effect of filler contents (0.5%, 1%, 1.5%, 2%, 3%, 5% and 7 vol.%) on the tribological properties was examined. The transfer films and the worn surfaces of the PTFE/PI composites filled with micrometer and nanometer TiO2 particles were investigated by using a scanning electron microscope (SEM). Experimental results show that anti-wear properties of the PTFE/PI composites can be improved greatly by filling nanometer TiO2 particles. The wear rate of 1.5% nanometer TiO2 filled composite is the lowest, which is about 52% lower than that of PTFE/PI. In the case of micrometer TiO2 filler, the friction coefficient and wear rates increase with increasing filler volume fractions under identical test conditions. It was also found that the wear mechanism of micrometer TiO2 particle-filled PTFE/PI is mainly severe adhesion and abrasive wear, while that of nanometer TiO2 particle-filled PTFE/PI is mainly slight abrasive wear.