Magnetic carbonyl iron suspension with organoclay additive and its magnetorheological properties

Soft magnetic carbonyl iron (CI) based magnetorheological (MR) fluids containing three different loadings of submicron-sized organoclay were prepared. The MR characteristics were measured via rotational and oscillatory tests, in which the flow curves exhibited a non-Newtonian behaviour for all investigated samples. The dynamic yield stress change was measured as a function of magnetic field strength by adopting a linear fit of the relation of log (tau(y)) proportional to log (H), which was originally applied for electrorheological fluids. The viscoelastic performances of the pure CI suspension and the CI/organoclay suspensions showed the existence of a solid-like character. The sedimentation ratio was also investigated to confirm the role of sub-micron organoclay particles on the MR properties, in which the dispersion stability of pure CI was improved with increasing the content of organoclay in the CI suspension. (C) 2010 Elsevier B.V. All rights reserved,