Tribological behaviour of oil-soluble organo-molybdenum compound as lubricating additives

摘要

A four-ball machine was employed to investigate the tribological performances and the synergetic function of organo-molybdenum compounds (molybdenum dialkyl-dithiophosphate and molybdenum dithiophosphate, coded as MoDDP and MoDTP, respectively) as additives in liquid paraffin. The morphologies of the worn surfaces and elemental distributions were observed and determined by means of scanning electron microscopy and energy dispersive spectrometry. The chemical states of some typical elements on the worn surface were analyzed on X-ray photoe-lectron spectroscope. The results show that MoDDP and MoDTP additives in liquid paraffin have excellent antiwear and friction-reduction properties, which are attributed to the reaction film composed of MoS_2 , FeS and MoO_2, and the deposited film composed of phosphate on the worn surface. Moreover, these two additives have synergetic friction-reducing and antiwear effect, which is closely related to the chemical states of S on the worn surface.