Tribological behavior and nature of tribofilms generated from fluorinated ZDDP in comparison to ZDDP under extreme pressure conditions—Part 1: Structure and chemistry of tribofilms

Tribofilms generated under boundary conditions at extreme pressure using lubricants containing fluorinated zinc dialkyl dithiophosphate (F-ZDDP) and zinc dialkyl dithiophosphates (ZDDP) were examined. F-ZDDP demonstrated superior wear performance compared to ZDDP even at lower phosphorus levels. The tribofilms generated by ZDDP and fluorinated ZDDP were analyzed using scanning electron microscopy, Auger electron spectroscopy and XPS. Transmission electron microscopy was conducted on wear debris. XANES spectroscopy was used to study the chemical and bonding environment of sulfur and phosphorus in these tribofilms. A phenomenological model of the tribofilms generated by ZDDP and fluorinated ZDDP was developed based on the experimental results.