Tribological properties of transfer films of PTFE-based composites

PTFE-based composites containing 15 vol.% MoS2, graphite, aluminum and bronze powder, were respectively prepared by compression molding at room temperature and subsequent heat treatment in atmosphere. Transfer films of pure PTFE and these composites were prepared on the surface of AISI-1045 steel bar using a friction and wear tester in a pin on disk contacting configuration. Tribological properties of these transfer films were investigated using another tribometer by sliding against GCr15 steel ball in a point-contacting configuration. Morphology of the transfer films and worn surface of the steel ball were observed and analyzed using SEM and optical microscopy. It was found all these fillers improved wear resistant capability of the composites. Compared with pure PTFE, introduction of the fillers made the corresponding transfer films have longer wear life. This is mainly attributed to strongly adhering transfer film and smaller wear debris particles lead by addition of the fillers. These smaller debris particles are prone to stay longer at the contacting region during the friction process. Introduce of fillers is helpful to improve load bearing capability of the transfer films when sliding against steel ball which are also favorable to prolong the wear life of the transfer films. Tribological properties of these transfer films are sensitive to load change. Generally, increased load shortened wear life of transfer film.