Regeneration of waste sintered Nd-Fe-B magnets to fabricate anisotropic bonded magnets

The waste sintered Nd-Fe-B magnets were regenerated as magnetic powders via manually crushing (MC) or hydrogen decrepitation (HD) to fabricate anisotropic bonded magnets. Effect of size distribution on the magnetic properties of the regenerated magnetic MC and HD powders was investigated. For the MC powders, as the particle size decreased, the remanence (Br) increased first, and then decreased again, while the coercivity (Hci) dropped monotonically. The powders with particle size in the range of 200–450 μm possessed the best magnetic properties of Br of 1.22 T and Hci of 875.6 kA/m. The corresponding bonded magnet exhibited magnetic properties of Br of 0.838 T, Hci of 940.9 kA/m, and (BH)max of 91.4 kJ/m3, respectively. On the other hand, the HD powders with particle size range of 200-450 μm bore the best magnetic properties of Br of 1.24 T and Hci of 860.4 kA/m. Compared with magnetic properties of the waste magnet, the powders retained 93.9% of Br and 70.0% of Hci, respectively. The bonded magnet produced from HD powders possessed Br of 0.9 T, Hci of 841.4 kA/m, and (BH)max of 111.6 kJ/m3, indicating its good potential in practical applications.

This figure is SEM photograph of the HD regenerated magnetic powders with size distribution of 200–450 μm. The HD powders bear the best magnetic properties of Br of 1.24 T and Hci of 860.4 kA/m. The bonded magnet produced from HD powders possesses Br of 0.9 T, Hci of 841.4 kA/m, and (BH)max of 111.6 kJ/m3, indicating its good potential in practical applicationsFigure optionsDownload as PowerPoint slide