The influence of surface properties on sliding contact temperature and friction for polyetheretherketone (PEEK)

Polyetheretherketone (PEEK) polymers are increasingly used in tribological applications. An important aspect of PEEK tribology is the surface temperature reached during sliding. At present, most knowledge of frictional heating in PEEK is based on post-hoc analysis of debris and wear surfaces. In this study, infrared thermography was used to observe the full field temperature map of PEEK against sapphire counterface during ball-on-disc sliding. The measured temperatures matched closely those predicted by flash temperature models. Additionally, friction studies were performed with steel and sapphire counterfaces. It was observed that PEEK debris readily deposited on steel but not on sapphire. The friction studies also indicated a greater adhesive friction response for PEEK against steel compared to PEEK against sapphire. The transfer of PEEK material to the steel surface may elevate the temperature at the sliding interface. Analysis of transfer films on steel suggests that the transferred PEEK was oriented in the direction of sliding. The deposition of debris and formation of oriented films resembled a high temperature drawing process, which was likely to be due to localized frictional heating. The results of this study illustrate the important role transfer films play in determining both the friction and temperature of the PEEK wear interface. (C) 2016 The Authors. Published by Elsevier Ltd.