ABSTRACTThe present work discusses the effect of the magnetic field on the friction and wear of steel sheets scratched by a steel insert at dry, lubricated by vegetable oils and dispersed by polymeric particles such as polyethylene (PE), polyamide (PA6) and polymethylmethacrylate (PMMA) Based on the experimental observations, it was found that friction coefficient displayed the highest values at dry sliding. Olive oil displayed the lowest values of friction coefficient followed by castor oil, almonds, maize, chamomile and jasmine oils. It seems that polar molecules of the tested vegetable oils can significantly improve the wear resistance developed by their strong adsorption on the sliding surfaces. Application of magnetic field on the sliding surface caused significant friction reduction at dry sliding. This behaviour may be from the magnetization of the steel which is known to be accompanied by reduction of plasticity and increasing the brittleness. Besides, magnetic field enhanced the ability of the oil molecules to orient themselves in relatively long chain adhered to the steel surface and thus decreased the friction and wear. Besides, the addition of polymeric particles such as PE, PA 6 and PMMA particles caused slight friction decrease as a result of the adhesion of those particles into the contact area. Further friction decrease was observed in condition of application of the magnetic field. Dry sliding gave the highest wear. The best wear resistance was observed for olive, maize, jasmine, castor, camomile and almonds oils. The polarity of oil molecules enhanced the oil to form a thick layer on the friction surface and consequently reduced the interaction of the insert into the scratch area. Under application of the magnetic field, wear slightly increased as a result of the reduction of plasticity and the increase of the brittleness, where the material removed from the groove scratched by the insert increased, while the material deformed in front and side ridges decreased. Presence of polymeric particles significantly decreased wear due to the ability of those particles to adhere into the insert/scratch track forming protective layer from excessive wear. In the presence of the magnetic field wear increased for polyethylene and polyamide. Magnetic field strengthened the adherence of PMMA particles into the cutting edges of the steel insert.
Abeer et al. (2011) studied this question.