An investigation of the effects of some motor oil additives on the friction and wear behaviour of oil‐soluble organomolybdenum compounds

Abstract

AbstractThe compatibility of oil‐soluble organomolybdenum compounds with some motor oil additives (detergent, dispersant, rust inhibitor and ZDDP) has been investigated on a four‐ball machine and a SRV tester. Preliminary results indicated that a combination of two agents might have either synergistic or antagonistic effects on the friction and wear performance of the organomolybdenum compounds, although many combinations were shown to be synergistic. The interactions between two agents were primarily determined by the additive types, additive concentrations and test temperatures.It was also found that the presence of calcium sulphonate detergent was particularly beneficial to molybdenum dithiophos‐phate and molybdenum dithiocarbamate in terms of friction reduction and wear reduction at temperatures in a certain range. The induction period of the organomolybdenum compounds was also reduced. Surface analysis results suggested that the synergistic effects were closely related to the formation of thick films, which were rich in molybdenum and sulphur, on rubbing surfaces.