A preparation method of high coercivity Nd-Fe-B magnet

Abstract

The invention relates to the field of magnetic materials and discloses a preparation method of a high coercivity NdFeB magnet, comprising the following steps: 1) slicing and surface treatment: slicinga sintered NdFeB magnet, then pretreating the surface of the magnet with dilute acid and alcohol respectively, and drying; 2) prepare a diffusion source: dissolving compound of dysprosium and/or terbium in absolute ethanol, adde inorganic acid salts of dysprosium and/or terbium with a mass not greater than 2. 5% of total compound of dysprosium and/or terbium, ultrasonically dispersing to obtain amixed liquid, attaching that mixed liquid on the surface of the magnet, drying, and forming a diffusion coating layer; 3) diffusion age treatment of magnet: heat preservation of magnet under reduce atmosphere. That invention adds specific content of dysprosium and/or terbium inorganic acid salt to diffusion source on the premise of not introducing too much impurity additive and not affecting thestructure (corrosion, oxidation, etc.) of magnet to improve the rare earth adhesion, so as to promote the effect of grain boundary diffusion.

Description

technical field [0001] The invention relates to the field of magnetic materials, in particular to a method for preparing a high-coercivity neodymium-iron-boron magnet Background technique [0002] In order to obtain permanent magnets with higher coercive force and magnetic flux, and reduce the doping amount of heavy rare earth elements, the process of grain boundary diffusion (Dy, Tb, Dy / Tb simple substance or compound) has become more and more manufacturing enterprises. s Choice. In the grain boundary diffusion process, the rare earth diffusion source must be attached to the surface of the magnet first, so that the subsequent diffusion process can proceed smoothly. Among the many attachment processes, dipping, coating, spraying, etc. are the most common. However, no matter which method is used, for grain boundary diffusion, the key to obtaining a high-performance magnet is to firstly obtain a layer of appropriate thickness, uniform concentration, and dense diffusion layer...

AI Technical Summary

Problems solved by technology

However, in this method, too much organic matter is introduced into the coating layer, which reduces the effective contact area between the diffusion source and the magnet, reduces the diffusion efficiency, and increases the difficulty of surface treatment of the magnet after diffusion.

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