Chemistry of ZDDP tribofilm by ToF-SIMS

Time-of-flight secondary ion mass spectrometry (ToF-SIMS) ( static and dynamic modes) has been applied to chemical characterization of zinc dithiophosphate additives tribofilm. Main result concerns insights in the spatial distribution of phosphate and sulphide species in the whole tribofilm thickness, at a sub-micrometer scale. The disappearance of oxide layer at the interface between steel and the tribofilm is also noticed.