Method for preparing highly coercive neodymium-iron-boron magnets with heavy rare earth Dy

Abstract

The invention belongs to the field of materials and particularly relates to a method for preparing highly coercive neodymium-iron-boron magnets with heavy rare earth Dy. The method includes: introducing a heavy rare earth diffusion source into pressed green blank in advance, and dipping the pressured green blank into a heavy rare earth complex organic solvent. On the one hand, organic coating of the surface of power particles is achieved to prevent powder from being oxidized, on the other hand, through decomposition of the heavy rare earth organic solvent during the sintering and heat treatment process, elements C and H evaporate into the gas, residual medium and heavy rare earth elements Tb / Dy spread to the surface of main-phase crystal particles to achieve magnetic hardening of the surface of the main-phase crystal particles, and magnetic coercivity is improved; in the method, the heavy rare earth diffusion source is added to the surface of the non-compact green blank in a dipping manner, multiple diffusion channels and deep diffusion depth are achieved, the diffusion methods of coating, steaming and rolling and the like on the sintered compact magnet surface in the conventionaldiffusion process are improved, extra long time high temperature diffusion treatment is not needed, and simple process and high diffusion efficiency are achieved.

Description

technical field [0001] The invention belongs to the technical field of permanent magnet materials, and in particular relates to a method for efficiently diffusing heavy rare earth Dy to prepare a high coercive force NdFeB magnet. Background technique [0002] After more than 30 years of development of sintered Nd-Fe-B magnets, the performance of the magnets has been continuously improved. The maximum magnetic energy product (BH)max experimental value of the magnet has reached 59.6MGOe, which is 93% of the theoretical limit value (theoretical 64MGOe). The experimental value of Br has also reached 1.55T, which is 97% of the theoretical value. There is limited space to further increase the remanence and energy product of the magnet, but the coercive force Hcj of the magnet is still low, which is 1 / 5-1 / 3. This largely limits the application of sintered Nd-Fe-B magnets in many fields, especially in some high-temperature fields. The most conventional and effective way to increas...

AI Technical Summary

Problems solved by technology

[0005] The purpose of the present invention is to overcome the problems of few diffusion channels, small diffusion depth, low efficiency and high energy consumption of heavy rare earth Dy element in the preparation process of NdFeB magnets in the prior art, so as to provide a high-efficiency diffusion preparation of heavy rare earth Dy. Coercivity NdFeB Magnet Method