A radio-tracer study of the effect of surface finish on the transfer of polychlorotrifluoroethylene sliding on mild steel.

Abstract

The effect of surface finish on the transfer of polychlorotrifluoroethylene (PCTFE) to mild steel was studied using a radio-tracer technique.

A pin-on-disk apparatus was used in conjunction with neutron activation of PCTFE to study the initial stages of transfer. Quantitative transfer and friction data were obtained as functions of surface finish and the number of repeated passes of polymer over mild steel. Qualitative supporting evidence for postulated transfer mechanisms was obtained using scanning electron microscopy.

The results showed that bulk transfer of PCTFE to mild steel does occur at room temperature. Initial transfer to polished (0.10 um - rms) surfaces, abraded (0.81 um - rms) surfaces, and glass bead blasted (1.73 um - rms) surfaces was attributed to an abrasive wear mechanism. An apparent translation to adhesive wear was observed during later stages of transfer. This transition occurred much sooner with the polished surface than with the rough surfaces.

This work also demonstrated that a radio-tracer technique could be effectively applied to the study of polymer wear. The minimum mass detection limit with this technique was 0.3 ug. This sensitivity is at least one order of magnitude better than that obtained with reported polymer wear measurement methods.