Preparation method of rare earth magnet

Abstract

The invention provides a preparation method of a rare earth magnet. The preparation method comprises the steps that the heavy rare earth raw material and an organic solvent are mixed for grinding, and a heavy rare earth suspension is obtained, wherein the solid-to-liquid ratio of the heavy rare earth suspension ranges from 0.1 g / ml to 0.6 g / ml, and the particle size of heavy rare earth power in the heavy rare earth suspension ranges from 50 nanometers to 300 nanometers; atomized spray is adopted to add the heavy rare earth suspension into neodymium-iron-boron powder, the heavy rare earth suspension and the neodymium-iron-boron powder are mixed to be uniform, and rare earth magnet powder is obtained, wherein the mass ratio of the heavy rare earth powder to the neodymium-iron-boron powder ranges from 0.1 wt% to 3.0 wt%; the rare earth magnet powder is subjected to pressing molding, sintering and heat treatment, and a neodymium-iron-boron magnet is obtained. According to the preparation method of the rare earth magnet, a multi-stage grinding process is adopted to produce a nano heavy rare earth additive; agglomeration of the heavy rare earth powder is prevented through interaction of the solvent and the heavy rare earth powder; a specific atomized spray device is used for atomizing the suspension carrying the nano heavy rear earth powder, and the atomized suspension carrying the nano heavy rear earth powder makes contact with and is mixed with the neodymium-iron-boron powder produced in a conventional way to be uniform.

Description

technical field [0001] The invention belongs to the field of rare-earth magnet manufacture, and in particular relates to a preparation method for significantly improving the performance of the rare-earth magnet and saving raw materials. Background technique [0002] Sintered NdFeB magnets have excellent magnetic properties and are widely used in many fields such as electronic information, automobile industry, medical equipment, energy and transportation. In recent years, there have been new applications in energy-saving and environmental protection fields such as wind power generation, energy-saving home appliances and new energy vehicles. Many of these applications require magnets to have good heat resistance, that is, not only require magnets to have a high maximum energy product (BH) max , but also requires a high intrinsic coercive force H cj , to reduce irreversible demagnetization during use, especially in environments with relatively high operating temperatures, and...

AI Technical Summary

Problems solved by technology

Although the second way of adding prevents heavy rare earths from entering the main phase grains in large quantities, the hydrogenated heavy rare earth coarse powder is easier to break than the main phase, and is more likely to form ultrafine waste powder that cannot enter the magnet; in addition, the obtained heavy rare earth powder has the same size as the main phase. The fine powder is equivalent, limited by the amount of addition, it is difficult to ensure that the heavy rare earth diffuses to the surface of each main phase powder during the sintering process

The third method is more obvious in improving the performance, but the heavy rare earth waste in the addition process is large and difficult to recycle. The high-concentration heavy rare earth layer formed on the surface of the magnet after the diffusion treatment will be worn off in the subsequent surface processing; very low rate

However, the technical plan does not mention how to obtain nano-scale additives; it also does not explain how to ensure that the nano-additives are evenly mixed with the NdFeB raw material powder

Moreover, although the addition of oxides solves the problem of anti-oxidation, it increases the oxygen content of the final magnet, which is not conducive to the improvement of magnetic properties and cost reduction.

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