Tribological Properties of Polytetrafluoroethylene with Mechanically Activated Carbon Fibers and Zirconium Dioxide

This paper presents an investigation into the mechanical and tribological properties of PTFE composites reinforced with mechanically activated carbon fibers (5-15 wt.%) and nano-sized zirconium dioxide (1 wt.%) under self-mated contact conditions using a pin-on-disk tribometer. Mechanical tests reveal that incorporating mechanically activated carbon fibers, with or without zirconium dioxide, into PTFE increases compressive strength by 57-71% and Shore D hardness by 17-21% compared to the unfilled polymer. The composite density, measured using the hydrostatic weighing method, decreases with higher filler content (5 to 15 wt.% carbon fibers) regardless of zirconium dioxide inclusion. Tribological tests demonstrate that PTFE reinforced with carbon fibers and nano-sized zirconium dioxide exhibits superior wear resistance compared to composites containing only carbon fibers. However, all composites show higher coefficients of friction and surface roughness Ra than unfilled PTFE under dry sliding conditions. IR spectroscopy reveals the new peaks corresponding to oxygen-containing functional groups, suggesting tribochemical reactions occurring on the worn surfaces. Scanning electron microscopy and optical microscopy were used to analyze the friction surfaces of the polymer matrix and polymer composites and the transfer film formed on the surface of the steel counterbody. In addition, the tribological properties are compared with industrial analog.