Effect of Additives on Tribological Performance of Magnetorheological Fluids

In this study, nano-diamond (ND) and MoS₂ powder are used as additives in a carbonyl iron-based magnetorheological fluid (MRF) to improve its tribological performance. MRFs are prepared by dispersing 35 wt.% of CI particles in silicone oil and adding different proportions (0, 1, 3, or 5 wt.%) of ND and MoS₂ additives. Seven kinds of MRFs are made and tested using reciprocating friction and wear tester under different normal loads, and then the friction characteristics are evaluated by analyzing the experimental results. The morphological properties of MRFs and contacting surfaces before and after the tests are also observed using a scanning electron microscope and analyzed via energy-dispersive X-ray spectroscopy. The results show that the appropriate weight percentage of MoS₂ additives may decrease the friction coefficient and wear zone. It is also demonstrated from detailed analyses of worn surfaces that the wear mechanism is influenced not only by additives, but also by the applied normal load and magnetic field strength.