Tribological Behavior of Metal Oxides Filled Polytetrafluoroethylene Composites under Water Lubrication

The friction and wear properties of several metal oxides filled polytetrafluoroethylene (PTFE) composites were evaluated on an MM200 test rig in ringonblock contact configuration. The worn surface morphologies of the composites under dry sliding and waterlubricated conditions were comparatively investigated by means of scanning electron microscopy, and the effect of various inorganic fillers on the friction and wear behavior of PTFE was discussed as well. The result indicated that metal oxide filled PTFEbased composites sliding against stainless steel had smaller friction coefficients and increased wear rates under water lubrication than under dry sliding. Under water lubrication, the filled PTFE composites registered increased friction coefficients and wear rates than pure PTFE. The high wear rate of the oxide filled PTFE composites could be attributed to the wetting action of the water as lubricant on filler, which subsequently weakened the linkage between the polymer matrix and the inorganic filler and hence reduced the wearresistance of the filled PTFE composites. The significantly high wear rates of the PTFE composites filled with inorganic salts might be attributed to the solving of the filler in water, which weakened the link between the filler and the polymer matrix and hence decreased the wearresistance of the composites.