Plate-like iron particles based bidisperse magnetorheological fluid

Abstract

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.

Dynamic and rate-dependent yielding behavior of Co0.9Ni0.1 microcluster based magnetorheological fluids

“…The magnetorheograms for both MR1 and MR2 characteristically displayed typical MR behavior. It is evident that a threshold shear stress is required to make the initial flow, which is a property of yield 5 stress fluid and this initial stress at very low shear rate (~0.001-0.1) is termed as static yield stress (τ ys ) [2,6,9]. With increasing field, initial stress required to make the fluid flow would also go higher, owing to the formation of more robust field-dependent interparticle network.…”

“…It consists of magnetic particles of micron to submicron (0.01-10 µm) dimensions, dispersed in carrier liquid [1][2]. The response of fluid under magnetic field is attributed to anisotropic, three-dimensional chain-like structures formed parallel to the direction of applied magnetic field.…”

“…The field-induced columnar structure can withstand external stress and has a potential for future magnetomechanical applications [5]. MR fluids have already been utilized in semi-active devices such as loudspeaker and microphone cone centering, tunable dampers and clutches [1][2][3][4][5].…”

Magnetorheological Payne effect in bidisperse MR fluids containing Fe nanorods and Fe3O4 nanospheres: A dynamic rheological study

“…Particularly, the origin of hump in G′′ curves in the frequency region 2-10 Hz is unclear. The viscous dissipation of energy is associated to hydrodynamic effect which can be attributed to internal movement of aggregates with increasing frequency [17]. But it is not yet clear which mechanism influences the magnitude and frequencydependent trend of G′′.…”

Magnetic Nanoparticles as a Redispersing Additive in Magnetorheological Fluid

“…The sedimentation phase is an inevitable phenomenon, inherent to the density difference between the components of the MRF [16], highly dependent on the electrochemical repulsive forces, which results from the interaction between electrolytes adsorbed to the surface material of the suspended magnetizable particles, and the composition of the dispersing phase [16,17]. Both the gravitational physical phenomena, centrifugal acceleration and electromagnetism [18][19][20], and the electrochemical forces result in the accumulation of the solid phase, forming the so called cake, in the bottom of the container. Several efforts have been made in order to improve the stability in magnetorheological suspensions, like adding iron particles to polymeric matrixes [21,22].…”