“…Since powder-sintered NdFeB (neodymium-iron-boron) rare earth permanent magnets were first reported in the 1980s, they have been widely applied in various different industrial fields, such as electronics, acoustics, micro wave technology, the auto industry, magnetic resonance imaging, wind power generators, new energy vehicles, magnetic separation technology, biomedical uses, etc., due to their excellent magnetic properties such as high remanence, high coercivity and a large maximum energy product [1][2][3][4][5]. However, the surface of a sintered NdFeB magnet is loose and porous because of the sintering process; moreover, the structure of the sintered NdFeB magnet is multiphase, and the potential difference between the phases is large.…”