[T16] Hard Magnetic Materials

[14E-T16-02] Field Assisted Sintering in the Direct Recycling of Hot Deformed Nd-Fe-B Magnet Scrap

*M. Keszler¹, F. Großwendt², A.-C. Assmann³, M. Krengel⁴, F. Maccari⁵, O. Gutfleisch⁵, D. Sebold¹, O. Guillon¹, S. Weber², M. Bram^{1, 2} (1.Forschungszentrum Jülich, Germany, 2.Ruhr-Universität Bochum, Germany, 3.RWTH Aachen University, Germany, 4.Wilo SE, Germany, 5.Technische Universität Darmstadt, Germany)

Keywords:permanent magnets, circular economy, field assisted sintering, recycling

Recycling of Nd-Fe-B magnets is an ongoing challenge for the goal of a circular economy. State-of-the-art magnet production methods have limitations with respect to direct recycling of magnet scrap particles. 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) has the potential to directly produce Nd-Fe-B magnets from 100% scrap material. A systematic study was done consolidating recycled magnet particles into a Flash SPS deformed magnet, using a range of weight percentages of scrap material and scrap particle size fractions. For example, H_cJ of >1400 kAm^-1 and B_r of 1.1 T could be achieved with 20 wt.% scrap material. The relationship between particle size fraction, oxygen uptake, and percentage of recyclate in a final magnet are all explored and discussed with respect to magnets made from pristine material.