Influence of particle shape on the properties of magnetorheological fluids

R. C. Bell, E. D. Miller, J. O. Karli, A. N. Vavreck, D. T. Zimmerman

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

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.

Original languageEnglish (US)
Title of host publicationProceedings of the 10th International Conference on Electrorheological Fluids and Magnetorheological Suspensions
Pages786-792
Number of pages7
StatePublished - Dec 1 2007
Event10th International Conference on Electrorheological Fluids and Magnetorheological Suspensions, ERMR 2006 - Lake Tahoe, NV, United States
Duration: Jun 18 2006Jun 22 2006

Publication series

NameProceedings of the 10th International Conference on Electrorheological Fluids and Magnetorheological Suspensions

Other

Other10th International Conference on Electrorheological Fluids and Magnetorheological Suspensions, ERMR 2006
CountryUnited States
CityLake Tahoe, NV
Period6/18/066/22/06

All Science Journal Classification (ASJC) codes

  • Fluid Flow and Transfer Processes

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  • Cite this

    Bell, R. C., Miller, E. D., Karli, J. O., Vavreck, A. N., & Zimmerman, D. T. (2007). Influence of particle shape on the properties of magnetorheological fluids. In Proceedings of the 10th International Conference on Electrorheological Fluids and Magnetorheological Suspensions (pp. 786-792). (Proceedings of the 10th International Conference on Electrorheological Fluids and Magnetorheological Suspensions).