Forschungszentrum Jülich GmbH
With growing interest in electric vehicles and renewable energy, recycling of Nd-Fe-B magnets will continue to become ongoing challenge for the goal of a circular economy. Due to the microstructure necessary for hot-deformed Nd-Fe-B permanent magnets, state-of-the-art magnet production methods have limitations with regards to the direct recycling of scrap magnet particles with anisotropic microstructure. Recent work has shown that a combination of pre-sintering by Field Assisted Sintering Technology/Spark Plasma Sintering (FAST/SPS) and hot deformation by Flash Spark Plasma Sintering (Flash SPS) can potentially produce Nd-Fe-B magnets directly from 100% scrap material. For gaining a better understanding of the possibilities of this novel approach, a systematic study was done to consolidate mixtures of recycled magnet particles and pristine melt-spun powder into a Flash SPS deformed magnet, using a range of weight percentages of scrap material and scrap particle size fractions. In some cases, HcJ of >1400 kAm-1 and Br of 1.1 T could be achieved with 20 wt.% scrap material. The relationship between oxygen uptake, particle size fraction, and percentage of recyclate in a final magnet are all explored and discussed in comparison to magnets produced only with pristine material.
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