TY - GEN
T1 - Influence of particle shape on the properties of magnetorheological fluids
AU - Bell, R. C.
AU - Miller, E. D.
AU - Karli, J. O.
AU - Vavreck, A. N.
AU - Zimmerman, D. T.
PY - 2007
Y1 - 2007
N2 - We present preliminary studies of the rheological properties and dispersion stability of MR fluids as a function of particle shape by comparing fluids made with uniform nickel spheres to those employing nickel microrods suspended in silicon oil. The rods were fabricated using template-hased electrodeposition having diameters in the range 300 ± 30 nm and lengths in the range of 5 - 25 μm. The properties of these rods were compared to commercial nickel carbonyl spheres (1-10 μm dia.). Qualitatively, the off-state (field off) viscosity of fluids containing only rods was found to be substantially greater than those that contain only spherical particles. Rheological measurements of the on-state viscosities were conducted using a custom rheometer equipped with an electromagnet capable of magnetic fields up to 0.6 T. Placed in this field, we observed yield stresses of 1.88 ± 0.23 and 1.86 ± 0.26 kPa, respectively for 7.6% volumc fraction of pure nickel spheres and rods, respectively. Due to limitations of the testing apparatus, only the on-state properties of these fluids were investigated. For this reason, the yield stress values reported do not account for the difference in off-state viscosity. While the fluids containing spherical nickel particles tended to settle rather quickly (< 20 minutes), those containing only rods remained suspended even after 48 hours.
AB - We present preliminary studies of the rheological properties and dispersion stability of MR fluids as a function of particle shape by comparing fluids made with uniform nickel spheres to those employing nickel microrods suspended in silicon oil. The rods were fabricated using template-hased electrodeposition having diameters in the range 300 ± 30 nm and lengths in the range of 5 - 25 μm. The properties of these rods were compared to commercial nickel carbonyl spheres (1-10 μm dia.). Qualitatively, the off-state (field off) viscosity of fluids containing only rods was found to be substantially greater than those that contain only spherical particles. Rheological measurements of the on-state viscosities were conducted using a custom rheometer equipped with an electromagnet capable of magnetic fields up to 0.6 T. Placed in this field, we observed yield stresses of 1.88 ± 0.23 and 1.86 ± 0.26 kPa, respectively for 7.6% volumc fraction of pure nickel spheres and rods, respectively. Due to limitations of the testing apparatus, only the on-state properties of these fluids were investigated. For this reason, the yield stress values reported do not account for the difference in off-state viscosity. While the fluids containing spherical nickel particles tended to settle rather quickly (< 20 minutes), those containing only rods remained suspended even after 48 hours.
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U2 - 10.1142/9789812771209_0109
DO - 10.1142/9789812771209_0109
M3 - Conference contribution
AN - SCOPUS:84864935144
SN - 9812771190
SN - 9789812771193
T3 - Proceedings of the 10th International Conference on Electrorheological Fluids and Magnetorheological Suspensions
SP - 786
EP - 792
BT - Proceedings of the 10th International Conference on Electrorheological Fluids and Magnetorheological Suspensions
PB - World Scientific Publishing Co. Pte Ltd
T2 - 10th International Conference on Electrorheological Fluids and Magnetorheological Suspensions, ERMR 2006
Y2 - 18 June 2006 through 22 June 2006
ER -