Fabrication of Sustainable 3D Printed Anisotropic Bonded Magnets Using Recycled Nd-Fe-B Powder and Low CO2 Footprint Polyamide 12

Polymer-bonded Nd-Fe-B magnets, made from hard magnetic powder and a polymer binder, are essential in many high-tech applications. The growing demand in energy-conversion devices calls for a more circular and versatile approach to their production. This study presents a sustainable approach to fabricate anisotropic polymer-bonded Nd-Fe-B magnets using recycled powder from end-of-life (EOL) hot-deformed magnets. Employing laser powder bed fusion with a low CO2 footprint polyamide 12 matrix in combination with magnetic powder enables production of complex geometries. Two methods are compared for converting EOL hot-deformed magnets into powder and the resulting performance of printed bonded magnets with these powders. Both powders have an elongated shape with the magnetic easy axis oriented perpendicular to the particle's length. Utilizing these anisotropic powders, based on a previously studied alignment mechanism, anisotropic bonded magnets are fabricated with over 60% higher magnetic performance compared to those made from EOL sintered magnet powders in 3D printing. The fabricated magnets have a remanence of 0.34 T and coercivity of 1238 kA m-1. The findings demonstrate a pathway toward turning parts of the magnet market into a more circular economy by reducing reliance on primary Nd-Fe-B sources and enhancing efficiency of magnetic powder use.