Regeneration of waste NdFeB sintered magnets via NdHX nanoparticles doping

In recent years, there is an increasing demand to recycle the waste NdFeB permanent magnets from both mass production and waste apparatus such as motors due to the rare earth resource limit and environmental protection. Up to now, many efforts have been devoted to the recycling works. Takeda et al. extracted Nd metal directly from NdFeB magnet scraps. Itoh et al. recycled rare earth containing sintered magnets to make isotropic bonded magnets by melt spinning. In our previous study, NdH_x nanoparticles were used to prepare regenerated sintered NdFeB magnets, and the coercivity of the magnet increased by 40% via the NdH_x nanoparticles doping. In the present study an attempt has been made to restore high coercivity in regenerated powders from waster NdFeB sintered magnets. The combination of degassing and chemical modification of particle surface of hydrogenation decrepitation (HD) NdFeB powders via NdH_x nanoparticles was used to prepare high coercivity powders and bonded magnets from the waste sintered NdFeB magnets. Magnetic properties of the regenerated magnetic powders and bonded magnets were investigated.