Micro-size high-performance sintered neodymium-iron-boron magnet and preparation method thereof

Abstract

The invention discloses a preparation method of a micro-size high-performance sintered neodymium-iron-boron magnet. The method comprises the steps of preparing low-melting-point heavy rare earth alloypowder, preparing an electrophoretic solution and carrying out electrophoretic deposition, wherein the electrophoretic solution preparation process comprises the step of dispersing the prepared low-melting-point heavy rare earth alloy powder into an anhydrous organic solvent to obtain a suspension, and the electrophoretic deposition process comprises the steps of taking a micro-size neodymium-iron-boron magnet as a cathode to be placed in the suspension for electrophoretic deposition, then drying the micro-size neodymium-iron-boron magnet subjected to electrophoretic deposition, and then carrying out heat treatment. The low-melting-point heavy rare earth alloy is introduced as a diffusion source; an electrophoresis method is used for deposition, the diffusion temperature is reduced, meanwhile, heavy rare earth elements are intensively distributed on the edges of crystal grains to form a core-shell structure, the grain boundary phase is improved, continuous distribution of the grain boundary phase is facilitated, the diffusion efficiency and the utilization rate of the heavy rare earth are improved, and the content of the heavy rare earth can be reduced by 30% compared with the prior art on the premise that the coercive force improvement degree is the same.

Description

technical field [0001] The invention belongs to the field of preparation of micro-sized NdFeB magnets, in particular to a micro-sized high-performance sintered NdFeB magnet and a preparation method thereof. Background technique [0002] The improvement of the coercive force of permanent magnets in the field of electroacoustics is mainly through the introduction of heavy rare earth elements through the alloy method or double alloy method to increase the coercive force of the magnet and then improve the overall performance of the magnet. The highest performance level of the magnets used in mobile phone speakers and receivers is: The force is 17-21kOe, the magnetic energy product is 50-52MGOe, the highest performance of the camera module VCM motor magnet: the coercive force is 25kOe, the magnetic energy product is 48MGOe, and the thickness of the magnet in the direction of the easy magnetization axis is required to be between 0.60 and 0.90mm. With the rapid landing of 5G techno...

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Problems solved by technology

The diffusion of the above fluoride will make the fluorine element remain in the magnet and cause the magnetic performance to deteriorate

At the same time, the diffusion temperature is high, the diffusion effect is not obvious, and the utilization rate of heavy rare earths is low

On the other hand, after electrophoretic diffusion, the batch processing of micro-sized magnets tends to cause large-scale mutual adhesion, which increases the workload in the later stage and affects the diffusion effect.

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