Research on the Tribological Performance of Cr_2O_3 Filled with Bronze-Based PTFE Composites

摘要

Enhancement of the wear resistance of bronze-filled polytetrafluoroethylene (PTFE) composites has been achieved using various fillers, for example, chromic oxide (Cr_2O_3), molybdenum disulfide (MoS_2), graphite, and nanometer aluminum oxide (n-Al_2O_3), in the present study. The wear resistance was evaluated by a block-on-ring wear tester, and the effects of fillers on the wear resistance as well as the mechanism were investigated. The wear rate for the composite where the recipe containing 59% PTFE + 40% bronze + 1% Cr_2O_3 was 0.5 × 10~(-5) mm~(-3)/N m and for the composite in the recipe containing 60% PTFE + 40% bronze was 4.2 × 10~(-5) mm~(-3)/N m, which meant that that Cr_2O_3 increased the wear resistance by approximately 10 times. The differential scanning calorimetry measure analysis showed that Cr_2O_3 had a positive effect on the crystallization of PTFE; the crystallinity of PTFE composites increased from 45% to 52%, which exhibited improved wear resistance. Wear testing and scanning electron microscope analysis had shown that Cr_2O_3 had a positive effect on the formation of transfer film and keeping it stable to exhibit improved wear resistance. X-ray photoelectron spectroscopy results also showed that Cr_2O_3 was effective in tribochemical reactions during sliding against stainless ring; these maybe responsible for forming transfer film and lowering wear rate of composite.