Study of the interaction between antiwear, extreme pressure and rust inhibitor agents in the formation of protective films by X-ray absorption spectroscopy

X-ray absorption near edge structure (XANES) spectroscopy at the P and S Ke dge has been used to characterize thermally generated films from antiwear ( AW)/extreme pressure (EP) agents such as organic phosphates and disulfides along with rust inhibitors such as alkylated organic acid/esters. The analy sis revealed that the AW additive formed an iron phosphate-like film on ste el and the EP agent formed an iron sulfate film on steel. From fluorescence yield XANES spectra, it was found that there exists a competition between the AW and EP agents.