EFFECT OF TEMPERATURE ON THE TRANSFER FILM FORMATION IN SLIDING CONTACT OF PTFE WITH STAINLESS-STEEL

The transfer of polytetrafluoroethylene (PTFE) to AISI 316 stainless steel during the first ten unidirectional traverses at room temperature, 100-degrees-C and 200-degrees-C was investigated. The amount of transferred PTFE was determined by detecting fluorine on the counterface utilizing the resonance of the nuclear reaction F-19(p, alpha-gamma)O-16 at a proton energy of 340 keV. The transfer of PTFE was observed to increase with increasing temperature and pin load, the deposition rate being the highest in all cases during the first traverse. During subsequent traverses, the transfer of PTFE still occurred and a constant deposition rate at a given temperature and nominal pressure was observed. The temperature dependence of the amount of deposited PTFE was modelled using the concept of a temperature enhancement factor, which was found to be independent of the number of traverses and was a function of temperature only. This indicates that bulk PTFE rather than the interface properties were affected by the increased temperature.