Hilmar Vidarsson

Development of permanent magnet MnAlC/polymer composites and flexible filament for bonding and 3D-printing technologies

Abstract Searching for high-performance permanent magnets components with no limitation in shape and dimensions is highly desired to overcome the present design and manufacturing restrictions, which affect the efficiency of the final devices in energy, automotive and aerospace sectors. Advanced 3D-printing of composite materials and related technologies is an incipient route to achieve functional structures avoiding the limitations of traditional manufacturing. Gas-atomized MnAlC particles combined with polymer have been used in this work for fabricating scalable rare earth-free permanent magnet composites and extruded flexible filaments with continuous length exceeding 10 m. Solution casting has been used to synthesize homogeneous composites with tuned particles content, made of a polyethylene (PE) matrix embedding quasi-spherical particles of the ferromagnetic τ-MnAlC phase. A maximum filling factor of 86.5 and 72.3% has been obtained for the composite and the filament after extrusion, respectively. The magnetic measurements reveal no deterioration of the properties of the MnAlC particles after the composite synthesis and filament extrusion. The produced MnAlC/PE materials will serve as precursors for an efficient and scalable design and fabrication of end-products by different processing techniques (polymerized cold-compacted magnets and 3D-printing, respectively) in view of technological applications (from micro electromechanical systems to energy and transport applications).

Manufacturing and microstructure of porous metal supports for a solid oxide fuel cell

Abstract One of the major drawbacks of a solid oxide fuel cell (SOFC) is the longtime stability. In order to have mechanical stability, the cell can be supported by a so-called porous metal support. These metal supports are usually manufactured by tape casting. This work, in contrast, is focused on processing these supports by different powder metallurgical techniques such as the press- and sinter route, gravity sintering or metal injection moulding. For some samples a shrinkage of 15% could be obtained as defined by the shrinkage of the ceramic functional layers (in case of desired “co-sintering an interval of 15–20% is preferable). The most promising manufacturing routes were found to be gravity sintering (about 50% porosity) and MIM (20–28% porosity): in both cases the pores are homogeneously distributed, and only slight agglomeration of pores can be seen.