Grain boundary diffusion preparation method of special neodymium-iron-boron permanent magnet for driving motor

Abstract

The invention provides a grain boundary diffusion preparation method of a special neodymium-iron-boron permanent magnet for a driving motor, which comprises the step that two rare earth-rich phase auxiliary alloys with high dysprosium content and high terbium content and a main phase alloy without dysprosium and terbium are designed, wherein the chemical formulas of the three alloys are (PrNd)20Dy20Fe<60-z-n>MzBn, (PrNd)30Tb10Fe<60-z-n>MzBn and (PrNd)xFe<100-x-z-n>MzBn respectively, x, z and n in the formulas respectively represent the mass percentages of corresponding elements in the formulas, and M is one or more of Zr, Nb, Ga, Co and Al. The method comprises the steps of firstly, preparing two main phase alloy components by adopting a double-alloy method, and then preparing the grain boundary diffusion base material by adopting a double-main phase alloy method. According to the preparation method, a double-alloy method and a double-main phase alloy method are utilized at the same time, and the magnetic performance of the base material can be greatly improved. Meanwhile, the content of heavy rare earth Dy and Tb can be better adjusted through the component proportioning mode of the preparation method, and the microstructure of the base material is optimized. Finally, the high-performance neodymium-iron-boron permanent magnets of various brands for the driving motor can be prepared by utilizing a grain boundary diffusion technology.

Description

technical field [0001] The invention belongs to the technical field of NdFeB permanent magnet materials and their preparation, and more specifically relates to a preparation method for grain boundary diffusion of NdFeB permanent magnets for drive motors. Background technique [0002] Drive motors for new energy vehicles mainly include permanent magnet synchronous motors and three-phase asynchronous motors. Among them, permanent magnet synchronous motors have the advantages of high efficiency, high torque density, small motor size, and light weight, and have become the mainstream of new energy vehicle drive motors. At present, permanent magnet synchronous motors are developing in the direction of high power, high functionality, miniaturization and environmental adaptability, making the requirements for magnet thickness and size more and more stringent. Higher requirements for thermal stability and performance consistency. At the same time, the competition among companies pro...

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Problems solved by technology

[0004] Physical vapor deposition methods include evaporation, magnetron sputtering, etc., which deposit rare earth elements on the surface of the magnet, and then diffuse into the interior of the magnet after diffusion treatment; this method can obtain a uniform coating with a controllable thickness and reduce the heavy rare earth The amount of elements used; but the vacuum sputtering equipment is expensive, the target preparation cost is high, and the film deposition speed is slow, which is not suitable for large-scale industrial production

Compared with the physical vapor deposition method, the electrochemical method has simple and economical equipment, short deposition time, and controllable thickness and uniformity; but the electrochemical method has high requirements for environmental protection

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