Permanent ferrite magnet which are currently found to have the highest commercial performance, are known as magnetic kings. They have the characteristics of small size, light weight and strong magnetism. With extremely high magnetic properties, its maximum magnetic energy product (BHmax) is more than 10 times higher than that of ferrite. Its mechanical processing performance is also quite good. The working temperature can be up to 200 degrees Celsius. And its texture is hard, its performance is stable, and it has a good price-performance ratio, so it is extremely widely used. But because of its strong chemical activity, it must be coated on its surface. (Such as Zn, Ni plating, electrophoresis, passivation, etc.).