A low friction and ultra low wear rate PEEK/PTFE composite

This paper presents a PEEK filled PTFE composite that exhibits low friction and ultra-low wear. It is hypothesized that a synergistic effect shuts down the dominant wear mechanism of each constituent. The friction coefficient and wear rate of this composite material on lapped stainless steel were evaluated for samples with PEEK wt.% of 0, 5, 10, 20, 30, 40, 50, 70 and 100 using a linear reciprocating tribometer. Tests were performed in filtered, standard laboratory conditions with a nominal contact pressure of 6.35 MPa, a speed of 50 mm/s and total sliding distances ranging from 0.5 km for the unfilled PTFE to 140 km for a 20 wt.% PEEK filled sample. The friction coefficients, averaged over an entire test, ranged from μ¯=0.111 for a 50 wt.% composite to μ¯=0.363 for unfilled PEEK. Wear rates ranged from K = 2.3 × 10−9 mm3/(Nm) for a 20 wt.% PEEK sample to K = 6 × 10−4 mm3/(Nm) for unfilled PTFE. Scanning electron microscopy revealed a unique interfacial connection between the PTFE and PEEK that is likely responsible for the ultra low wear rates observed in these experiments.