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Magnetic field dependent steady-state shear response of Fe3O4 micro-octahedrons based magnetorheological fluids

Abstract

We report the synthesis of single crystalline octahedron-shaped magnetite microcrystals, preparation of magnetorheological fluids (MRFs) and their magnetorheological properties under steady-state shear conditions. The magnetite microcrystals were synthesized via template-free hydrothermal route. MRFs with three different particle concentrations (10, 20 and 40 weight%) were prepared and were subjected to steady shear conditions at various externally applied magnetic fields of strength up to 1.2 T. The shear rates were chosen up to high enough values to observe the yield behaviour of the MRFs. The dynamic yield strengths of MRFs, estimated using Bingham plastic model fit to the steady-state shear response curves, showed that they scale-up with the applied magnetic field strength and amount of magnetic particles in the fluid. The origin of the mechanical strength in the MRFs due to the inter-particle interaction is explained using a simple dipolar model. The observed high yield strengths of the MRFs were explained on basis of the particle shape (octahedrons) and magnetic nature (saturation magnetization). Comparing the values of yield strength with on-state to off-state viscosity for the MRFs (for each particle concentration), optimum content of particles in carrier fluid to obtain high efficiency is suggested. The particles being single crystalline, the off-state viscosity of the MRFs even at highest studied (40 wt%) particle concentration was very low, which is ideal for their application in quickly responding MRFs.

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Publication details

The article was received on 12 Apr 2018, accepted on 06 Jul 2018 and first published on 13 Jul 2018


Article type: Paper
DOI: 10.1039/C8CP02335B
Citation: Phys. Chem. Chem. Phys., 2018, Accepted Manuscript
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    Magnetic field dependent steady-state shear response of Fe3O4 micro-octahedrons based magnetorheological fluids

    A. V. Anupama, V. B. Khopkar, V. Kumaran and B. Sahoo, Phys. Chem. Chem. Phys., 2018, Accepted Manuscript , DOI: 10.1039/C8CP02335B

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