Magnetorheology and sedimentation behavior of an aqueous suspension of surface modified carbonyl iron particles

Surface modified carbonyl iron particles (SMCIPs) were synthesized by coating carbonyl iron particles with an organic reagent (N-polyether, N, N, N,-acetyloxy) 2, 6-aminion-1, 3, 4-thiadiazole dimer. The properties of these SMCIPs, including morphology, structure, and magnetic behavior, were characterized using scanning electron microscopy and a vibrating sample magnetometer. Aqueous magnetorheological (MR) fluids were prepared using SMCIPs. MR properties were measured via a strain-controlled parallel disk rheometer equipped with a magnetic field source. Addition of the organic surface coating layer was found to greatly improve sedimentation stability of the aqueous MR fluids at a small cost of a reduction in field dependent yield stress. (C) 2010 American Institute of Physics. [doi:10.1063/1.3358613]