The tribological behaviour and tribochemical mechanism of action of oxovanadium (IV)-dithiophosphate

Vanadium (IV)-oxo-dicyclodithiophosphate (VDTP) was prepared and its additive properties evaluated using a four-ball machine. The results show that VDTP exhibits better extremepressure performance, but lower antiwear activity, when compared with ZDTP. The reaction film composition, characterised by scanning Auger microscopy (SAM), X-ray photoelectron spectroscopy (XPS) and diffractometer surface techniques, reveals that the antiwear and friction layer containing vanadium oxide, phosphate/phosphide, and sulphide, prevent the rubbing pairs from contacting directly, resulting in better extreme-pressure and antiwear behaviour.