There are many types of magnets, which are generally divided into two categories: permanent magnets and soft magnets. The magnets we are talking about generally refer to permanent magnets. The following is a brief introduction to the classification of magnets.

Permanent magnets are divided into two categories:

1. Metal alloy magnets include neodymium iron boron magnets (Nd2Fe14B), samarium cobalt magnets (SmCo), aluminum nickel cobalt magnets (ALNiCO)

2. Ferrite permanent magnet materials (Ferrite)

1. Neodymium iron boron magnet: It is the magnet with the highest commercial performance found so far. It is called the king of magnets. It has high magnetic properties and its maximum magnetic energy product (BHmax) is more than 10 times higher than ferrite (Ferrite). Its own mechanical processing performance is also quite good. The working temperature can reach up to 200℃. Moreover, it has a hard texture, stable performance, and a good cost-effectiveness, so it is extremely widely used. However, because of its strong chemical activity, it is necessary to coat its surface. (Such as Zn, Ni plating, electrophoresis, passivation, etc.)

2. Ferrite magnet: Its main raw materials include BaFe12O19 and SrFe12O19. It is made by ceramic process, with a relatively hard texture and brittle material. Due to its good temperature resistance, low price and moderate performance, ferrite magnet has become a widely used permanent magnet.

3. Al-Ni-Co magnet: It is an alloy composed of aluminum, nickel, cobalt, iron and other trace metal elements. The casting process can be processed into different sizes and shapes with good machinability. Cast Al-Ni-Co permanent magnet has a low reversible temperature coefficient and the operating temperature can be as high as 600°C. Al-Ni-Co permanent magnet products are widely used in various instruments and other applications.

4. Samarium cobalt (SmCo) is divided into SmCo5 and Sm2Co17 according to its composition. Its development is limited due to its high material price. As a rare earth permanent magnet, Samarium cobalt (SmCo) not only has a high magnetic energy product (14-28MGOe), reliable coercive force and good temperature characteristics. Compared with NdFeB magnets, SmCo magnets are more suitable for working in high temperature environments.