Dresden 2017 – scientific programme
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MA: Fachverband Magnetismus
MA 10: Caloric Effects in Ferromagnetic Materials
MA 10.7: Talk
Monday, March 20, 2017, 17:00–17:15, HSZ 04
Influence of particle orientation on the effective thermal conductivity of magnetocaloric composites — •Kai Sellschopp1, 2, 3, Bruno Weise2, 3, Marius Bierdel2, 3, Alexander Funk2, 3, Manfred Bobeth3, Maria Krautz2, and Anja Waske3 — 1TU Hamburg-Harburg — 2IFW Dresden — 3TU Dresden
Plates of epoxy-bonded La-Fe-Si-type particles display improved mechanical stability compared to sintered La-Fe-Si-type plates. The magnetocaloric properties are maintained very well in these composites and they are easy to process. However, the effective thermal conductivity (ETC) is decreased because of the low thermal conductivity of the epoxy. Our idea to overcome this problem without changing the volume fraction of magnetocaloric material is to produce an anisotropic ETC which prefers the out-of-plane direction, thereby enhancing heat transport to the heat exchange fluid. Using the anisotropic shape of the particles this can be achieved by orienting the particles' largest dimension in the out-of-plane direction.
Based on a real 3D data set obtained from X-ray computed tomography (XCT) several particle orientation distributions were modeled using equivalent ellipsoids for the description of particle shape. The ETC tensor was calculated from FEM simulations for all scenarios to study the influence of particle orientation on ETC. The simulations showed that orientation of the particles in the out-of-plane direction can increase the out-of-plane ETC by over 25%.