SLIDING WEAR MECHANISM OF POLYTETRAFLUOROETHYLENE (PTFE) AND PTFE COMPOSITES

The previous literature regarding the wear of polytetrafluoroethylene (PTFE) is discussed, as are the mechanistic theories proposed to date for wear reduction via fillers. The mild-severe transition for unfilled PTFE is investigated as a function of sliding speed and temperature, and guidelines for maintenance of mild wear are developed. A fracture-based model describes the onset of severe wear and attendant changes in debris morphology. The wear-reducing effectiveness of three fillers is investigated as a function of speed. Under severe sliding conditions (when fillers are most effective) it is proposed that fillers reduce wear by interrupting subsurface deformation and crack propagation which would otherwise lead to large wear sheets.