ABSTRACTThe present work investigates the influence of magnetic field on the friction coefficient displayed by sliding of steel pin on polyamide disc lubricated by paraffin oil and dispersed by different lubricant additives such as zinc dialkyldithiophosphates (ZDDP), molybdenum disulphide (MoS2), heteropolar organic based additive (CMOC), graphite (C), detergent additive (calcium sulphonate) (DA), polytetrafluroethylene (PTFE) and polymethyl methacrylate (PMMA). Based on the experiments carried out in the present work, it was found that, at surfaces lubricated by paraffinic molecules friction coefficient decreased with increasing applied load. As the magnetic field increased friction coefficient increased. When the oil was dispersed by ZDDP additive significant decrease of friction was observed. The performance of ZDDP additive was not affected by application of the magnetic field. Dispersing Mo S2 or C in the lubricating oil caused significant friction increase. The effect of magnetic field on performance of MoS2 was insignificant, while magnetic field caused slight friction reduction in the presence of C. Magnetic field decreased friction coefficient when the oil was dispersed by CMOC. Under the action of magnetic field the force of adhesion significantly increased causing proper surface coating which caused the friction decrease. Oil dispersed by calcium sulphonate showed significant friction decrease due to the polarity of its molecules. Application of magnetic field caused further friction decrease. As a result of the quite good response of DA additive with magnetic field based on the values of friction coefficient observed for the oil dispersed by DA additive, it can be recommended to use this additive when magnetic field is applied. The good lubricating properties observed for PTFE additive can be from its ability to form a layer on the sliding surfaces. PTFE particles dispersed in the oil were much influenced by magnetic field, where the lowest value was displayed at the highest intensity of magnetic field. The same trend of friction decrease was observed for PMMA particles dispersed in oil.
Zaini et al. (2012) studied this question.