Rare earth magnet, method for producing same, and motor provided with same

By performing particle boundary diffusion and restriction grinding in NdFeB-based rare earth magnets, the problem of performance degradation in the surface particle boundary phase of the magnet is solved, and a rare earth magnet with high coercive force and dimensional accuracy is achieved.

CN119694699APending Publication Date: 2025-03-25TOYOTA JIDOSHA KK
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Patent Information

Application Number
CN202411305839.6
Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
Priority Date
2023-09-20
Filing Date
2024-09-19
Publication Date
2025-03-25

AI Technical Summary

Technical Problem

After grinding and processing of rare earth magnets, there is a particle boundary phase on the surface of the magnet that is not rich in rare earth elements, resulting in a decrease in magnet performance, especially the coercive force and residual magnetization.

Method used

By performing particle boundary diffusion in NdFeB-based rare earth magnets and performing limited grinding, the dimensional accuracy and coercivity of the magnet are ensured.

Benefits of technology

While ensuring dimensional accuracy, the high coercive force of NdFeB-based rare earth magnets is maintained, avoiding the phenomenon of low magnetic field demagnetization.

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Abstract

The invention relates to a rare earth magnet, a manufacturing method thereof and a motor provided with the rare earth magnet. Provided is an R-T-B-based rare earth magnet having excellent magnetic characteristics while ensuring dimensional accuracy. The R-T-B-based rare earth magnet according to the present invention is an R-T-B-based rare earth magnet in which R is a rare earth element, T is Fe and / or Co, and B is boron, the R-T-B-based rare earth magnet having a magnet region layer and a surface layer covering the C-plane of the magnet region layer, the magnet region layer having a main phase having an R2T14B-type crystal structure and a grain boundary phase, and the grain boundary phase having a grain boundary structure. The grain boundary phase is present around the main phase, the average particle diameter of the main phase is 1.0 [mu] m to 10.0 [mu] m, and the surface layer covers the C-plane of the magnet region layer in an amount of 85% or more relative to the total area of the C-plane.
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