Changes in the surface morphology of polycarbonate induced by fretting

Abstract

Although fretting damage is normally associated with contacting metal surfaces subjected to relative oscillatory slip of a few microns amplitude, it can also occur when polymers are in contact with metals. The fretting damage between polycarbonate-steel surfaces is made up of iron oxide debris from the steel surface and the formation of cracks on, and fibres from, the polymer surface. Cracking and flow is the result of hysteretic heating arising from the low thermal conductivity and relatively high damping capacity of the polymer. Since the rate of heating is dependent on the energy imparted to the process, increasing the amplitude of slip reduces the time to cracking and polymer flow. Neither cracking nor flow is influenced by gaseous environments and sites producing fibres remain active until the encroachment of iron oxide from adjacent slip regions gradually stifles fibre formation.