Method for preparing sintered neodymium iron boron through grain boundary diffusion of heavy rare earth

Abstract

The invention provides a method for preparing sintered neodymium iron boron through grain boundary diffusion of heavy rare earth. The method comprises the steps that heavy rear earth matter and organic solvent are mixed to prepare turbid liquid; the turbid liquid is subjected to dispersion treatment in neodymium iron boron alloy powder, and neodymium iron boron powder is obtained; and after being heated, cooled and sieved, the neodymium iron boron powder is subjected to compression molding, sintering and aging treatment, and the sintered neodymium iron boron is obtained. According to the method, the heavy rear earth matter and the neodymium iron boron alloy powder are sintered, so that the heavy rear earth matter and the neodymium iron boron powder are mixed evenly, the preparation process is simple, the using amount of the heavy rear earth matter is small, and the utilization rate of the heavy rear earth matter is high; meanwhile, the coercivity and temperature resistance of the sintered neodymium iron boron are improved, and the consistency of properties of the sintered neodymium iron boron is guaranteed.

Description

technical field [0001] The invention relates to a processing technology for preparing sintered NdFeB by diffusing heavy rare earth in the grain boundary, especially improving the grain boundary diffusion process of sintered NdFeB, improving the composition of sintered NdFeB as a whole, and improving the coercive force and Process for temperature resistance. Background technique [0002] Sintered NdFeB is the most cost-effective permanent magnet material today, known as the "magnet king". Compared with other permanent magnets, the local temperature of sintered NdFeB is low, which is the main factor restricting its application in industry. In order to improve the temperature resistance of sintered NdFeB, people have tried various methods. Among the existing conclusions, the antiferromagnetic coupling characteristics of heavy rare earths can offset the low local temperature brought about by the ferromagnetic coupling of light rare earths. problem, but the stock of heavy rare ...

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Problems solved by technology

Japanese scholars first developed the model of grain boundary diffusion. Diffusion of heavy rare earths into magnets by coating and heat treatment shows that the coercive force and temperature resistance are greatly improved. The disadvantages are obvious, because only coated It is applied to the surface of the material, so its diffusion depth is only limited to the micron level, which leads to the fact that the process can only process thin sheet permanent magnet materials, and has limited effect on large rare earth permanent magnets; some domestic research institutions have studied the method of double alloy mixing , but the mixing effect is not ideal, mainly due to the poor dispersion of the heavy rare earth compound itself, especially the powder that reaches the nanometer level has poor fluidity and is easy to agglomerate, and it has a high melting point, which cannot be well mixed with iron when sintered at high temperature Neodymium boron is sintered together, and defects such as holes and sand holes appear, resulting in low magnetic properties and poor squareness; in addition, the simple powder mixing method cannot achieve efficient dispersion and cannot fully exert the role of heavy rare earths

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