Geometry effect of different PTFE fillers on self-lubricating PF composites: Mechanical and tribological properties

In order to further improve the performance of polytetrafluoroethylene (PTFE) as lubricant additives, PTFE fiber bundles (PTFE-F) were prepared by wet spinning to enhance phenolic resin (PF), and PTFE powders (PTFE-P) were used as a contrast phase. PF-based composites were prepared by hot pressing sintering, and their tribological properties were tested by ball-on-disc friction tests. The results showed that the shore hardness and compressive strength of PF-15 wt% PTFE-F were severally 5.8 % and 58.6 % higher than that of PF-15 wt% PTFEP. The COF of PF-15 wt% PTFE-F and PF-15 wt% PTFE-P were 0.102 and 0.088, while the wear rates were 2.53 x 10-7mm3/Nm and 1.59 x 10-4 mm3/Nm respectively, with a difference of 628 times. It has been demonstrated that the transfer film formed on the friction pair ball is multi-layer structure, which formed by the physical adhesion of PTFE and the tribochemical reaction between the PTFE and the steel ball. Therefore, the geometry effect idea can be used to fabricate a new kind of self-lubricating materials applied widely in the fields of navigation, aviation, and aerospace.