Magnetic Carbonyl Iron Suspension with Sepiolite Additive and Its Magnetorheological Property

Sepiolite, a fibrous clay mineral, was introduced to a soft magnetic carbonyl iron (CI) particle based magnetorheological (MR) fluid to improve its sedimentation problem, in which the MR fluid is a colloidal suspension of magnetizable particles dispersed in a nonmagnetic carrier. The MR characteristics of two MR fluid systems with and without a sepiolite additive were evaluated and compared under different magnetic field strengths using a rotational rheometer, exhibiting typical MR behaviors. Scanning electron microscopy images indicate that the sepiolite filled the interspaces among CI particles, therefore preventing a severe sedimentation problem and improving dispersion stability of the MR fluid. Sedimentation of the MR fluid was also characterized by an optical analyzer system of Turbiscan.