Anisotropy of the magnetoviscous effect in a cobalt ferrofluid with strong interparticle interaction
Anisotropy of the magnetoviscous effect in a cobalt ferrofluid with strong interparticle interaction
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DOI：
10.1016/j.jmmm.2015.08.029
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发表时间：
2015-12-15
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.
The anisotropy of the magnetoviscous effect (MVE) of a cobalt ferrofluid has been studied in a slit die viscometer for three orientations of the applied magnetic field: in the direction of the fluid flow (Delta eta(1)), the velocity gradient (Delta eta(2)), and the vorticity (Delta eta(3)). The majority of the cobalt particles in the ferrofluid exhibit a strong dipole-dipole interaction, which corresponds to a weighted interaction parameter of lambda(w) approximate to 10.6. Thus the particles form extended microstructures inside the fluid which lead to enhanced MVE ratios Delta eta(2)/Delta eta(1) > 3 and Delta eta(3)/Delta eta(1) > 0.3 even for strong shearing and weak magnetic fields compared to fluids which contain non-interacting spherical particles with Delta eta(2)/Delta eta(1) approximate to 1 and Delta eta(3)/Delta eta(1) = 0. Furthermore, a non-monotonic increase has been observed in the shear thinning behavior of Delta eta(2) for weak magnetic fields < 10 kA/m, which cannot be explained solely by the magnetization of individual particles and the formation and disintegration of linear particle chains but indicates the presence of heterophase structures. (C) 2015 Elsevier B.V. All rights reserved.
