There are many types of magnets, generally divided into two categories: permanent magnets and soft magnets.
Permanent magnets are further divided into two categories:
The first category is: metal alloy magnets, including Neodymium-Iron-Boron magnets, Samarium Cobalt magnets, and Aluminum-Nickel-Cobalt magnets.
The second major category is: Ferrite permanent magnet materials.
(1) Ferrite magnet: The main raw materials of ferrite include BaFe12019 and SFe12019. It has a relatively hard texture and is a brittle material. Because ferrite magnet has good temperature resistance, low price and moderate performance, it has become the most widely used permanent magnet.
(2) Neodymium-Iron-Boron magnet (NdFeB): It is the magnet with the highest commercial performance currently found. It is known as the magnet king. It has extremely high magnetic properties and its maximum magnetic product (BHmax) is 10 times higher than that of Ferrite. The machining performance itself is also quite good. The operating temperature can reach up to 200 degrees Celsius. Moreover, its texture is hard, its performance is stable, and it has good cost performance, so its application is extremely wide. However, because of its strong chemical activity, its surface must be treated with a coating. (Such as Zn, Ni plating, electrophoresis, etc.).
(3) Samarium Cobalt magnets (SmCo) are divided into SmCo5 and Sm2Co17 according to their different components. Its development is limited due to the high price of raw materials. SmCo magnet not only has a high magnetic energy product (14-28MGOe), strong coercivity and good temperature characteristics. Compared with NdFeB magnets, SmCo magnets are more suitable for working in high temperature environments.