Investigation of counterface surface topography effects on the wear and transfer behaviour of a POM–20% PTFE composite

In order to gain greater insight into the relation between the wear rate, counterface surface topography and the characteristics of the transfer layer formed, a series of wear experiments have been performed with a commercial POM–20% PTFE composite sliding against hardened tool steel counterfaces in a pin-on-plate reciprocating configuration. The surface topography of the steel counterface with respect to the sliding direction was varied by unidirectionally grinding parallel and perpendicular to the sliding direction, and by grit blasting. By varying the grinding and grit-blasting parameters, plates of various roughnesses were produced. The form and composition of transfer layers were studied using optical microscopy and SEM/EPMA. The type and composition of the transfer layer formed were found to depend on the counterface surface topography and four types of transfer layer could be distinguished. The steady-state wear rate of the polymer was found to be influenced by both the surface topography of the steel counterface and by the characteristics of the transfer layer formed after running in.