Tribological behavior and nature of tribofilms generated from fluorinated ZDDP in comparison to ZDDP under extreme pressure conditions—Part II: Morphology and nanoscale properties of tribofilms

Tribofilms generated using lubricants containing zinc dialkyl dithiophosphate (ZDDP) and fluorinated zinc dialkyl dithiophosphate (F-ZDDP) were examined. Nanoindentation yielded reduced elastic modulus and hardness as a function of the penetration depth of the nano-indenter for different loading conditions. The mechanical strength of the tribofilm was evaluated by conducting scanning wear and nano-scratch tests. Results indicate that load used to create the tribofilms plays an important role in determining their hardness with the tribofilms formed at higher loads exhibiting higher hardness. Tribofilms formed from F-ZDDP were more resistant to scratch and wear compared to ZDDP tribofilms. FIB measurements indicate F-ZDDP tribofilms were thicker than ZDDP tribofilms.