Research progress of fabrication Sm-Fe-N bulk magnet with high density

Abstract:

Samarium iron nitrogen compound (Sm2Fe17N3) has become research hotspot of new rare earth permanent magnet materials because of its higher magnetocrystalline anisotropy field and Curie temperature value and less rare earth content than neodymium iron boron (Nd2Fe14B). However, since samarium iron nitrogen will decompose at 600 °C resulting the disappearance of permanent magnetic properties, the conventional high-temperature sintering process is not suitable for the preparation of samarium iron nitrogen sintered magnets and it can only be compounded with polymer materials as plastic magnets, which results in that the magnetic properties of Sm2Fe17N3 cannot be fully exerted. Therefore, the development of low-temperature forming process to prepare all-metal bulk magnets with high density is the key to obtaining high-performance samarium-iron-nitrogen magnets. After more than 30 years of hard work, researchers have developed a variety of low-temperature rapid prototyping processes for preparing samarium-iron-nitrogen magnets, and obtained high-performance magnets with a maximum magnetic energy product of 25MGOe. Starting from the preparation method of magnets, this paper summarizes the current research status and problems of bulk samarium-iron-nitrogen magnets, especially analyzes the phenomenon of coercivity decline in different fabrication methods, and makes prospect for its future development.