Tribological Sensitivity of PTFE/Alumina Nanocomposites to a Range of Traditional Surface Finishes

摘要

Wear tests were performed with polytetrafluoroethylene (PTFE) + Al{sub}2O{sub}3 nanocomposites on various manufactured surfaces to determine whether or not the wear resistance of these nanocomposites is a strong function of surface preparation. Four different surface finishes of grade 304 stainless steel counterfaces were used: electropolished (R{sub}q = 88 nm), lapped (R{sub}q = 161 nm), wet-sanded (R{sub}q = 390 nm), and dry-sanded (R{sub}q = 578 nm), PTFE + Al{sub}2O{sub}3 nanocomposites made from powders of roughly 2-20 μm PTFE (matrix) and ～44 nm Al{sub}2O{sub}3 (filler) were prepared at filler weight percentages of 0, 1, 5, and 10% and tested on each surface finish. Additionally, 5 wt% 44-nm nanocomposites were compared to identically prepared 5 wt% 80- and 500-nm Al{sub}2O{sub}3 filled PTFE composites on each surface. Friction coefficients were between 0.12 and 0.19 and wear rates decreased from K = 810 × 10{sup}(-6) mm{sup}3/(Nm) for the 5 wt% 500-nm alumina-filled PTFE on the dry-sanded surface to K= 0.8 × 10{sup}(-6) mm{sup}3/(Nm) for the 5 wt% 80-nm filled composite on the lapped surface. It was found that the minimum wear rate occurred on the lapped counterface for every composite, and the wear rate is a strong function of the transfer film thickness and morphology.