Model scale generation and microscopic characterisation of tribofilms formed on Fe and Cu alloys

The layer‐forming properties of different lubricants on technically used tribosystems were investigated. The experiments were carried out on a ring‐on‐disc test set‐up on Fe/Fe‐ and Fe/Cu‐based systems. Three different lubricants were used viz. base oil with detergents (Oil‐A), oil with ZnP‐based additives (Oil‐B) and oil with P‐based additives (Oil‐C). We measured the electrical resistance between the rubbing surfaces. Surface characterisation (light microscopy, SEM/EDX and XPS) and tribometric results show differences in wear and friction properties. Oil‐B showed profound layer formation on steel counterparts and correlation in the amount of Zn and S, P and O, respectively; whereas, none of the above was observed with Oil‐A. Oil‐C, however, showed thin but tribologically effective layer formation on ferrous system and a superior performance for the Fe/Cu system.