A method for improving the magnetic properties of sintered NdFeB by grain boundary diffusion

Abstract

The invention discloses a method for improving the magnetic performance of sintered NdFeB through grain boundary diffusion, and belongs to the technical field of rare earth magnetic materials. The method comprises the steps that sintered NdFeB magnetic powder is subjected to semi-densification sintering, wherein the density is 90-95%; the periphery of the semi-densification sintered NdFeB is coated with turbid liquid, with the viscosity of 100-500 mpa.s, containing heavy rare earth compounds, the vacuum drying is carried out, coatings with heavy rare earth elements areobtained on the surface of a semi-densification sintered NdFeB magnet, then sintering at 1040-1080 DEG C is carried out for 2-3 h, primary tempering at 900-940 DEG C is carried out for 1-3 h, secondary tempering at 480-550 DEG C is carried out for 2-4 h, and the high-magnetism sintered NdFeB material is obtained. Certain adhesive force is formed between the semi-densification sintered NdFeB magnet and the coatings such as Dy2O3, Tb2O3, DyF3 and DyH3, the heavy rare earth elements enter the NdFeB magnet in the sintering process, the organizational structure and components at the combined position of a grain boundary and a main phase are improved, the heavy rare earth elements can be more easily diffused into the NdFeB magnet, the distribution uniformity and thickness consistency are high, and the depth of the diffusion layer is greatly increased.

Description

technical field

[0001] The invention belongs to the technical field of rare earth magnetic materials and provides a method for improving the magnetic properties of sintered NdFeB by grain boundary diffusion. Background technique

[0002] Sintered NdFeB permanent magnet material is the third generation permanent magnet, which was invented by Japanese scholars in 1983. Because of its extremely high coercive force and magnetic energy product, it is called "Magnetic King". NdFeB rare earth permanent magnet materials currently occupy more than 60% of the permanent magnet material market share. With the development of new energy systems such as hybrid electric vehicles (HEV), pure electric vehicles (EV) and wind power generation, in permanent magnet materials The sintered NdFeB permanent magnet material with the highest magnetic energy product is the key to realize the miniaturization, light weight and high power of the motor.

[0003] After more than 20 years of research and de...

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