Reduced Friction-Wear of Polymer Composites by Poly(ether imide) (PEI)-Induced Transfer Film Adhesion

A poly(tetrafluoroethylene) (PTFE) and polyether ether ketone (PEEK)-based composite incorporating molybdenum disulfide (MoS2) and PEI was successfully developed through material compounding technology to significantly enhance the wear resistance and reduce the friction coefficient of engine main shaft bearing cages. The tribological properties, transfer film composition/morphology, and friction-reducing/antiwear mechanisms of composites with different formulation ratios were systematically investigated. Through regulated composition optimization, the PEI single-filler composite demonstrated superior tribological performance compared to PEI/MoS2 cofilled systems. The friction coefficient of the best formulated sample was about 0.09 and the wear rate was 2.56 × 10–5 mm3/(N·m). The results demonstrated that the incorporation of PEI enhanced the interfacial stability and improved the adhesion of the transfer film. Compared with pure PTFE material, the composite formed a thin, uniform transfer film with higher coverage on the bearing steel ball surface during friction. The results of this work are expected to provide a functional filler for improving the tribological properties of PTFE-based self-lubricating composites. Furthermore, the superior performance of the formulation without MoS2 suggests that enhancing transfer film adhesion can be a more critical factor than the incorporation of conventional layered solid lubricants in this system. This work provides another theoretical perspective for functional filler selection.