Experimental investigations on the process of forming functional microstructured blades from highly filled thermoplastic composites prepared with La(Fe, Si)13 alloys

International audienceHighly loaded polymer extrusion and forming processes are low-cost manufacturing processes which use con-tinuous polymer profiles to elaborate magnetocaloric composites and 2D structured thin components and shapethem into a wide variety of materials. The development of functional composites involves various requirements,specifications, and composite component designs. A composite must exhibit a high shear viscosity for polymerextrusion processing and permit extremely high loadings of solids to produce functional magnetocaloric prop-erties which are equivalent to those of bulk materials. A composite material based on highly loaded magneto-caloric composites was elaborated and investigated by using gas-atomised La(Fe,Si)13alloys. This appears to beuseful in the fabrication of functional structured magnetocaloric components as regenerators or blade shapes. Inthe present study, composite elaborations were investigated with specific focus on the homogeneity and rheo-logical behaviours for a powder size distribution between 13 and 143μm, solid loadings of 35%–65% by volume,and shear rates of 102–103/s. The binder used was based on different thermoplastic polymers with low meltingtemperatures, such as polypropylene or low-density polyethylene, to avoid dehydrogenation of the magneto-caloric powders during the material-forming process. The shaping of structured blades by highly loaded polymerprocessing from the compounding to the forming process through the development of innovative processes anddedicated extrusion lines equipped with well-designed microstructured thin-blade-forming tools was studied.Thin structured blades of thickness 0.5 mm were obtained with micropatterns of width 200μm, with the max-imal efficiency being 92%. The Curie temperature was determined from the powder stage to the mixing processand thefinal material shaping to validate the magnetocaloric properties and quantify the limits of the meth-odologies developed with different powders (the Curie temperature was adjusted to−21 and 23.5 °C). In thisregard, the elaborated composite and the structured thin extruded component were characterised in terms of thehomogeneity, magnetocaloric properties, and dimensional and geometric tolerances