Tribological Behaviors of PTFE-Based Composites Filled With Nanoscale Lamellar Structure Expanded Graphite

This paper provides a polytetrafluoroethylene (PTFE)/nano-EG solid self-lubricating composite that exhibits very low friction coefficient and wear rate. In present study, the influences of the content of expanded graphite with nanoscale lamellar structure (nano-EG) in PTFE/nano-EG composite, normal contact pressure, and sliding velocity on tribological properties were studied by using the MMU-5G friction and wear tester sliding against AISI-1045 steel. Meanwhile, the property of nano-EG was characterized by utilizing a field emission scanning electron microscope. Compared with that of pure PTFE, the addition of nano-EG into PTFE matrix effectively improved the antifriction and wear resistance properties of PTFE/nano-EG composite. The highest wear resistance was found for the PTFE/nano-EG composite filled with $15wt%$ nano-EG. The morphologies of worn surface of the ANSI-1045 steel and composites were observed using a confocal laser scanning microscopy (CLSM) and a scanning electron microscope (SEM) to examine composite microstructures and to study modes of failure. The images of CLSM and SEM indicate that the property of transfer film generated on the surface of mating pair is likely responsible for the lower wear rate observed in these experiments.