Chemical and mechanical analysis of tribofilms formed from fully formulated oils Part 2 – Films on Al–Si alloy (A383)

Abstract

The interactions of a commercially available fully formulated oil on an Al–Si alloy have been studied, and a chemical and mechanical characterisation of the resulting surface films has been undertaken to compare with the results found on 52100 steel. ZnS and Ca phosphate are the primary species found. No Mo species were found in the film, but B was detected; the latter observation contrasts with the results found for 52100 steel. A surprisingly consistent indentation modulus was found for the films formed on A383, considering the complex microstructure of the alloy, which has been shown previously to influence the mechanical response of the film produced from zinc dialkyl dithiophosphates (ZDDPs) in oil. The stiffness of the films on A383 is statistically indistinguishable from that found on 52100 steel, and the topography of the film also looks unchanged compared to the steel study.