Rare earth permanent magnetic materials are alloys composed of samarium and neodymium mixed rare earth metals and transition metals (such as cobalt, iron, etc.), which is a kind of magnetic material prepared by pressing mould sintering by powder metallurgy and magnetizing by magnetic field. Rare earth permanent magnet
is divided into Sm Co (SmCo) permanent magnet and NdFeB (NdFeb) permanent magnet. The magnetic energy product of SmCo magnets is between 15--30MGOe, the magnetic energy product of NdFeb system magnets is between 27--50MGOe, which is called "permanent magnet king", it is the most magnetic permanent magnet material. Samarium cobalt permanent magnet, despite its excellent magnetic properties, contains rare earth metals, samarium and cobalt, and expensive strategic cobalt. Therefore, its development has been greatly restricted. The development of the rare earth permanent magnet industry in China began in the late 1960s, the dominant product at the time was samarium - cobalt permanent magnet, Sm-Co permanent magnets sold 630 tons worldwide and 90.5 tons in China, (including SmCo magnetic powder), mainly used in military technology.
It is divided into the first generation (RECo5), the second generation (RE2TM17) and the third generation rare earth permanent magnet material (NdFeb). New rare earth transition metals and rare earth Fe-N permanent magnet alloys are being developed and are likely to be a new generation of rare earth permanent magnet
With the development of computer, communication and other industries, the rare earth permanent magnet
, especially Nd-FeB permanent magnet industry has developed rapidly.
Rare earth permanent magnet is one of the most widely known permanent magnet materials, the magnetic properties of the magnetic steels used in the 1990s are 100 times higher than those of ferrite, aluminum, nickel and cobalt, and twice as high as those of expensive platinum-cobalt alloys. Since the use of rare earth permanent magnetic materials has not only promoted the development of permanent magnetic devices towards miniaturization and improved the performance of products, but also promoted the production of some special devices, the emergence of rare earth permanent magnetic materials has immediately aroused great attention throughout the country, its dvelopment is extremely rapid. The properties of various rare earth permanent magnet materials developed and produced in China are close to or up to the international advanced level.