Friction behaviour and structure of boundary lubrication film for a molybdenum dithiolate anti-wear additive

Abstract

The friction, anti-wear and interface reaction characteristics of molybdenum toluene-3, 4-dithiolate (Mo(TDT) 3) were studied by static reaction and friction tests. Mo(TDT) 3 shows better load-carrying capacity and anti-wear properties compared with zinc dialkyl dithiophosphate (ZDDP), but not as good as molybdenum dialkyl dithiophosphate. The distinct feature of the Mo(TDT) 3 additive is the smoothing effect on the rubbing surface. The surface analysis of the surface reaction film shows that Mo(VI) and Mo(IV) both exist on the surface, but Mo(IV) exists mainly on the subsurface. No significant difference in molybdenum distribution was observed between terrace and track on the rubbing surface, although the sulphur concentration on the terrace was higher than that on the track. The static reaction indicated that below 175°C, only the Mo(VI) state was found on the iron surface. However, the difference between the static reaction and friction test of the molybdenum state indicated that friction induced the reductive reaction which results in the transition of Mo(VI) to Mo(IV).