-- Do all sintered NdFeB magnets need coating?Sintered NdFeB permanent magnet materials are produced by powder metallurgy process. It is a powder material with very strong chemical activity. There are tiny pores and cavities inside, which are easily corroded and oxidized in the air. The experimental results show that a 1cm³ sintered NdFeB permanent magnet will be completely oxidized and corroded when placed in air at 150°C for 51 days. After the magnetic material is corroded or the components...