Study of the effects of Ca sulfonate on antiwear film formation by X-ray absorption spectroscopy using synchrotron radiation

Abstract

X-ray absorption near edge (XANES) spectroscopy at the P and S L-edge and K-edges has been used to characterize antiwear films generated from combinations of the antiwear additives, zinc dialkyl dithiophosphates (ZDDPs), and the detergent additives, Ca sulfonates. The results clearly show the interaction of the detergent with the ZDDP in antiwear film formation. Zinc polyphosphate, in part, is converted to calcium phosphate. There are substantial differences between the effect of the neutral and overbased detergents. Wear is also affected by the presence of the detergent.