Plate-like iron particles based bidisperse magnetorheological fluid

Magnetorheological (MR) properties are experimentally investigated for bi-dispersion suspension of plate-like iron magnetic particles dispersed in carrier liquid to see the influence of small size particle on large size MR fluid. As a first step, structural, magnetic, and morphology of two different micron size magnetic particles are described in details. The three different weight fractions of MR fluid samples are then prepared, followed by measuring their magneto-viscous and visco-elastic properties. In the steady-state shear, the Bingham yield stress obtained by extrapolating the shear stress to the zero shear rate increases by augmenting the weight fraction of small micron size magnetic particles and the strength of magnetic field. In the oscillatory strain sweep test at an angular frequency of 10 rad s(-1), a transition from visco-elastic solid to visco-elastic liquid is observed and a strong chain formation is proposed to explain the mechanism for transition. The storage modulus also increases with increasing weight fraction. From the frequency sweep test, the storage modulus is seen as independent of frequency, but depends on the magnetic field strength and weight fraction. The magneto-viscous sweep test indicates that both shear modulus and complex viscosity are independent with weight fraction at a high magnetic field. This experimental study reveals some very important physical parameters, rheological properties, and storage modulus of the plate-like iron particles based on MR fluid. The formation of less compact because of the anisotropy in iron particle creates weak sedimentation and good redispersibility of MR fluid. The results presented in this work are the key factors for devising how mechanical applications operated under static and dynamic conditions. (C) 2013 AIP Publishing LLC.