ToF-SIMS analysis of phosphate-type lubricant additives adsorbed on friction surfaces of ferrous materials

The adsorption of phosphate-type lubricant additives on ferrous materials h as been investigated by time-of-flight secondary ion mass spectrometry (ToF -SIMS) of friction surfaces. Eight kinds of model compounds were used for t he friction tests. In ToF-SIMS spectra of the friction surfaces after washi ng with hexane, Fe-alcoholates were detected as reaction products of alcoho l units of the additives and the ferrous material, and Fe-polyphosphate was detected as a reaction product of a phosphate unit and the ferrous materia l. The quasi-molecular ions of model compounds, which suggest the existence of physical adsorption, were detected in some of the lubricant systems. Th e amounts of these products were found to be correlated with lubrication pr operties such as friction coefficient and width of wear scar. Copyright (C) 2001 John Wiley & Sons, Ltd.