A method for improving the magnetic properties of sintered NdFeB magnets

Abstract

The invention relates to the technical field of permanent magnet preparation, and discloses a method for improving the magnetic properties of sintered NdFeB magnets, which includes the following steps: preparing RM alloy powder, wherein metal R is one or more of heavy rare earth element metals, metal M is one or more of Al, Cu, Mg, Fe, Co, Nb, Zr, Ga; the adhesive and antioxidant are mixed and dissolved in absolute ethanol to obtain an organic coating; the RM alloy powder is dispersed in absolute ethanol Diffusion paint is formed in the process, and the diffusion paint is coated on the surface of the sintered NdFeB magnet, and then the organic paint is sprayed quickly, and after drying, the diffusion treatment is carried out at 700 ° C ~ 1000 ° C and the tempering treatment is carried out at 400 ° C ~ 600 ° C. In the present invention, an RM coating is first formed on the surface of the sintered NdFeB magnet, and then an organic protective layer is sprayed on the outside of the RM coating. Finally, the organic protective layer is decomposed before the diffusion treatment, which effectively improves the coercive force of the magnet and does not affect the magnet. magnetic.

Description

technical field [0001] The invention relates to the technical field of permanent magnet preparation, in particular to a method for improving the magnetic performance of a sintered NdFeB 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 promotion speed and application range of sintered NdFeB magnets in high-end fields such as wind power, inverter compressors, and hybrid power have rapidly expanded. The market has put forward higher requirements for their performance, not only requiring high remanence, but also High coercive force is required. [0003] The existing method to improve the coercive force of sintered NdFeB magnets is mainly to add heavy rare earth elements such as Dy or Tb to sintered NdFeB magnets. Heavy rare earth elements such as Dy or ...

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Problems solved by technology

[0008] The purpose of the present invention is to overcome the problem in the prior art that the coercive force of NdFeB magnets is generally increased by adding rare earth metal powder or rare earth compounds, but when adding rare earth metal powder, the particle size of rare earth metal powder is required to be small, while rare earth metal powder The surface activity is high, it is unstable in the air, and it is easy to react and generate heat; when rare earth compounds are used, there are generally other elements such as O, F, and H in the rare earth compound powder. These impurity elements enter the interior of the magnet, which not only affects the magnetic properties after diffusion, but also Problems that will affect the physical properties of magnets, etc., provide a method to improve the magnetic properties of sintered NdFeB magnets, use alloy powders of heavy rare earth metals and other metals to form RM alloy coatings, and spray on the outside of RM to form an organic protective layer , and finally carry out diffusion treatment and tempering treatment so that the RM in the RM alloy coating enters the interior of the sintered NdFeB magnet, and the organic protective layer decomposes and detaches from the magnet. While significantly increasing the coercive force, it ensures that the remanence does not decrease significantly. and can be mass-produced

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