Tribological behaviour of carbon-nanofibre-reinforced poly(ether ether ketone)

The influence of vapour-grown carbon nanofibres (CNF), of average diameter 150 nm, on the wear behaviour of semicrystalline poly(ether ether ketone) (PEEK) was investigated. Unidirectional sliding tests against two different counterpart materials (100Cr6 martensitic bearing steel, and X5CrNi18-10 austenitic stainless steel) were performed on injection moulded PEEK-CNF nanocomposites. The specific wear rates of the nanocomposites were measured as a function of filler loading fraction and the results are compared to a variety of commercial PEEK grades. Analysis of the wear behaviour, and examination of the wear surfaces, revealed a variety of effects compared to the control materials. Most importantly, the carbon nanofibres were found to reduce the wear rate of PEEK significantly. In the light of these promising results, combinations of nanofibres with the conventional fillers, polytetrafluoroethylene and/or carbon fibres, were explored; it was found that such optimised compounds can be used to tailor the wear properties of the PEEK-CNF compounds.