Tribochemical driven interfacial energy gradient in ultralow wear PTFE composite

Previous studies of certain ultralow wear PTFE composites highlighted the wear rate's extremely high sensitivity to the interfacial surface energy gradient (Delta gamma) with a scale factor of nearly 104 times per mJ/m2. This study aims to further elucidate the origin of such gradient and its relation with wear reduction by systematically studying wear and tribofilm's environmental sensitivities of a 5 wt% PPS-PTFE composite. The results found a scaling factor between wear rate and Delta gamma of about 1000 fold per mJ/m2. Results also suggest that the interfacial energy gradient is directly driven by transfer film adhesion and coverage, transfer film adhesion is dominated by PTFE tribochemistry rather than PPS enrichment, and a moderate Delta gamma minimizes bulk wear and stabilizes transfer films.

Automated summary

This study aims to further understand the origin of the interfacial surface energy gradient and its relationship with wear reduction by investigating the wear and environmental sensitivities of a 5 wt% PPS-PTFE composite. The results reveal that there is a scaling factor of approximately 1000 fold per mJ/m2 between wear rate and Delta gamma. It is also found that the interfacial energy gradient is influenced by transfer film adhesion and coverage, which is primarily determined by PTFE tribochemistry rather than PPS enrichment. Additionally, maintaining a moderate Delta gamma can minimize bulk wear and stabilize transfer films.