Nanoporous Fe-MCM-22 Additive Effect on Magnetorheological Response of Magnetic Carbonyl Iron Suspension

A magnetorheological (MR) fluid, composed of soft magnetic carbonyl iron (CI) particles dispersed in a nonmagnetic carrier fluid, was prepared with an additive of nanoporous Fe-MCM-22 particles. Fe-MCM-22 was synthesized by a hydrothermal method and was used to prevent fast settling of the CI particles in the MR fluid system. Two MR fluids comprised of the same CI particles in 25% volume fraction were prepared, but one having additional 5 wt% Fe-MCM-22 according to the carrier fluid weight. Performance of these MR fluids, including shear stress, shear viscosity and yield stress, were measured using a rotational parallel disk rheometer in a steady flow. Suspension stability and magnetic properties were also examined by a Turbiscan apparatus and a vibrating sample magnetometer, respectively. The addition of Fe-MCM-22 into the CI suspension was found to improve not only MR properties including field dependent yield stress, but also dispersion stability of the suspension.