Application of ellipsometry to the characterization of reaction films formed by ZnDTPs on sliding steel surfaces

Spectroscopic ellipsometry (SE) was used to determine the thickness of zinc dialkyldithiophosphate (ZnDTP) reaction films formed on steel surfaces. Simultaneous measurements of friction coefficient and electrical contact resistance (ECR) were carried out using a cylinder-on-disk tribometer to form ZnDTP reaction films under a sliding condition, with monitoring of both the change of friction and the formation of ZnDTP reaction films during sliding. The film thickness was obtained by regression fitting of the data generated by the dispersion model to the experimental data. The results indicated that the thickness of the reaction film influenced the friction behavior of ZnDTP.