Anisotropy of the magnetoviscous effect in a ferrofluid with weakly interacting magnetite nanoparticles
Anisotropy of the magnetoviscous effect in a ferrofluid with weakly interacting magnetite nanoparticles
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DOI：
10.1088/0953-8984/27/17/176001
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发表时间：
2015-05-08
影响因子：
2.7
通讯作者：
Odenbach, S.
中科院分区：
文献类型：
--
作者：
Linke, J. M.;Odenbach, S.
在一个特殊设计的狭缝模粘度计中研究了磁流体的磁粘效应的各向异性，该粘度计允许磁场相对于流体流动的三个不同方向。根据剪切速率和磁场强度确定了相应的Miesowicz粘度系数，以获得流体的全面磁流变特性。流体中的颗粒具有13 nm的平均直径，对应于磁铁矿的λ近似于1.3的相互作用参数。因此，当磁场强度增加且剪切速率降低时，可以预期流体显示出从非相互作用的单个颗粒到具有链状缔合颗粒的微结构的转变。所观察到的磁场和剪切相关的磁粘效应的各向异性解释相干在流体中的这些微观结构的变化。
The anisotropy of the magnetoviscous effect of a ferrofluid has been studied in a specially designed slit die viscometer, which allows three distinct orientations of the magnetic field with respect to the fluid flow. The corresponding Miesowicz viscosity coefficients were determined in dependence of the shear rate and the magnetic field intensity to gain a comprehensive magnetorheological characterization of the fluid. The particles in the fluid have a mean diameter of 13 nm corresponding to an interaction parameter of lambda approximate to 1.3 for magnetite. Thus, the fluid can be expected to show a transition from non-interacting individual particles to microstructures with chain-like associated particles when the magnetic field intensity is increased and the shear rate is decreased. The observed field and shear dependent anisotropy of the magnetoviscous effect is explained coherently in terms of these microstructural changes in the fluid.