Thermoplastic filled with magnetocaloric powder

Highlights: • Formulation of a thermoplastic highly loaded in magnetocaloric powder is proposed. • Rheological behaviour shows a good processability in extrusion and injection moulding. • Curie point of magnetocaloric composite is impacted by the mixing temperature. • Dehydrogenation of magnetocaloric powders is observed at the temperature of 200 °C. - Abstract: Magnetic refrigeration is an innovative and promising alternative to traditional refrigeration systems. This technology does not require refrigeration gases and offers a high thermodynamic efficiency, reducing the global environmental impact associated with the process. However, the production of magnetocaloric components used as regenerators in magnetic refrigeration systems is a significant challenge. This work consists of developing an innovative process to obtain magnetocaloric components by powder injection or extrusion moulding. A component containing up to 91.5 wt.% magnetocaloric powder was obtained using a gas atomised magnetocaloric powder La–Fe–Si alloy patented by Erasteel. The powder is first mixed with a thermoplastic polymer to obtain a "ready to shape" feedstock. Then, the feedstock is either injected or extruded to obtain the magnetocaloric component. Characterisations of the thermo-physical and mechanical properties are carried out during all stages of processing, from pure powder to injected parts. A study on the modification of the Curie temperature as a result of dehydrogenation was performed during each processing stages. Good processability was demonstrated for the highly loaded feedstock and conservation of the magnetocaloric properties during the process. Finally, the process does not induce any mass loss and allows the production of stable pieces containing a giant magnetocaloric effect.