Effects Of Key Process On The Structure And Magnetic Properties Of Sintered Nd-Fe-B Magnets

With the development of the society and the innovation of science and technology, the applications of Nd-Fe-B permanent magnetic material have been extended to all areas of human society, because of its high magnetic properties. Especially in national defense, communication, wind power generation, hybrid cars, medical facilities and other fields play a key role. According to the small scale of enterprises, the backward of equipments and technology, the stability and consistency in magnetic properties should be further improved.In this paper, some key processes and equipments of sintered Nd-Fe-B permanent magnetic material are introduced, such as strip casting, hydrogen decrepitation and jet milling process, rubber isostatic pressing process, sintering and annealing process etc., the effects of which on the structure and magnetic properties of magnets are investigated. It is mainly show that the effects of powder structure, shape, particle size distribution, magnetic field orientation and the magnetic properties by HD+Jet Milling process, which has been compared with traditional processes. The temperature characteristics, microstructure and magnetic properties of the sintered Nd-Fe-B magnets with addition of Dy、Nb have been studied. It is found that Dy addition results in smaller grains and more homogeneous and regular grain structure, Hcj increases with increasing Dy content and the irreversible loss of magnetic flux decreases. It is considered that Hcj increases with increasing Nb content and the irreversible loss of magnetic flux decreases. As a result, the irreversible loss of magnetic flux decreases notably and the magnetic properties at higher temperature are improved.