Method for improving magnetic properties of sintered neodymium-iron-boron thin-sheet magnet

Abstract

The invention discloses a method for improving magnetic properties of a sintered neodymium-iron-boron thin-sheet magnet. According to the method, the surface of the sintered neodymium-iron-boron thin-sheet magnet is coated with powder containing rare earth elements to form a surface coating layer, and diffusion treatment and aging treatment are carried out to allow the rare earth elements in the coating layer to enter the interior of the sintered neodymium-iron-boron thin-sheet magnet, wherein the powder containing the rare earth elements is a mixture of powder of rare earth oxide and powder of hydrogen storage alloy hydride. The method has the advantages that oxidation-reduction reaction is carried out between the rare earth elements and the hydrogen storage alloy hydride, the rare earth elements are reduced, hydrogen is released from the hydrogen storage alloy hydride during diffusion treatment, thus, the diffusion efficiency of the rare earth elements is remarkably reduced, the diffusion depth of the rare earth elements is increased, the content difference of the rare earth elements at different positions in the sintered neodymium-iron-boron thin-sheet magnet is reduced, the coercive force is obviously increased, and residual magnetism reduction is ensured not to be obvious; and moreover, mass production can be achieved, and the final squareness of the sintered neodymium-iron-boron thin-sheet magnet cannot be affected.

Description

technical field [0001] The invention relates to a method for improving the magnetic performance of a sintered NdFeB magnet, in particular to a method for improving the magnetic performance of a sintered NdFeB thin slice magnet. Background technique [0002] Sintered NdFeB magnets have excellent comprehensive magnetic properties and are widely used in aerospace, microwave communication technology, automobile industry, instrumentation and medical equipment and other fields. In recent years, the high-performance sintered NdFeB application market has rapidly developed in the direction of miniaturization, light weight and thinning. The promotion speed and application scope of high-end fields such as hybrid power are rapidly expanding, and the market has put forward higher requirements for its performance, not only requiring high remanence, but also requiring high coercive force. [0003] The traditional method to improve the coercive force of sintered NdFeB thin slice magnets is...

AI Technical Summary

Problems solved by technology

However, this method has the following problems: when rare earth metal powder is used, rare earth elements are more likely to enter the interior of the sintered NdFeB sheet magnet during the diffusion process, and the coercive force is significantly improved under the premise that the remanence is not significantly reduced, but Rare earth metal powders are unstable in the air environment, and atmosphere protection is required in the process of storage and surface coating formation, and it is difficult to carry out mass production; when rare earth compound powders are used, the rare earth compounds are more stable in the air environment. There is no need for atmosphere protection in the process of storage and surface coating, but the rare earth compound is not easy to decompose during the diffusion treatment, so that it is difficult for the rare earth element to diffuse into the sintered NdFeB thin sheet magnet, resulting in the sintered NdFeB thin sheet magnet. The improvement of the coercive force is not obvious, and it will affect the squareness of the final sintered NdFeB thin film magnet

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