There are many kinds of magnets, generally divided into two categories: permanent magnet and soft magnet. Aamagnet gives a brief introduction to magnet classification.
Permanent magnet can be divided into two categories:
1、 Metal alloy magnets include Nd2Fe14B, SmCo and AlNiCo magnets
2、 Ferrite permanent magnet
1. Neodymium iron boron magnet: it is a magnet with high commercialization performance, known as the "king of magnetism", with high magnetic properties, its large magnetic energy product (BHmax) is more than 10 times higher than that of ferrite. Its own machining performance is also quite good. The working temperature can be as high as 200 ℃. Moreover, it is hard in texture, stable in performance and good in cost performance, so it is 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 technology. It is hard and brittle. Because of its good temperature resistance, low price and moderate performance, ferrite magnet has become a widely used permanent magnet.
3. Alnico magnet: 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 alnico permanent magnet has a low reversible temperature coefficient, and its working temperature can be as high as 600 ℃. Alnico permanent magnet products are widely used in various instruments and other applications.
4. SmCo can be divided into SmCo5 and Sm2Co17 according to different components. Because of the high price of its materials, its development is limited. As a rare earth permanent magnet, SmCo not only has high magnetic energy product (14-28mgoe), reliable coercive force and good temperature characteristics. Compared with NdFeB magnets, SmCo magnets are more suitable for working at high temperature.
