NdFeB magnet and surface passivation process of NdFeB magnets

摘要

The invention relates to an NdFeB magnet and a process for the surface passivation of neodymium-iron-boron permanent magnets. To prevent corrosion, it is proposed to provide the magnet with an alpha -Fe2O3 coating having a thickness of between 0.5 and 5 mu m. For this purpose, the preferably ground magnet is subjected to an annealing treatment in an oxidising atmosphere at temperatures between 600 DEG C and the sintering temperature.