Carbon nanotube coated magnetic carbonyl iron microspheres prepared by solvent casting method and their magneto-responsive characteristics

In order to improve not only the magnetorheological (MR) properties of soft magnetic carbonyl iron (CI) but also its dispersion stability, we fabricated a dense network of multi-walled carbon nanotubes (MWCNTs) on the surface of CI particles by using 4-aminobenzoic acid as a grafting agent through a two-step method: ultrasonication and solvent casting, based on the self-assembly of MWCNTs which have a similar density to the polymer but better magnetic properties due to the iron catalyst located in the MWCNT. The influence of coating layers on magnetic properties along with MR performance such as yield stress behavior and shear viscosity were investigated by a vibrating sample magnetometer and rotational rheometer. The suspension stability was found to be improved from a Turbiscan test.