Grain boundary diffusion method suitable for large rare earth permanent magnet material

Abstract

The invention discloses a grain boundary diffusion method suitable for a large rare earth permanent magnet material. A spark plasma sintering technology is used for carrying out grain boundary diffusion treatment on a magnet, and the comprehensive magnetic performance of the magnet is improved. The method comprises the following steps: (1) preparing an initial magnet through a sintering or hot pressing or thermal deformation process; (2) loading a grain boundary diffusion alloy source on the surface of the magnet through magnetron sputtering, electroplating, chemical vapor deposition, physicalvapor deposition, direct physical contact or bonding by a binder; and (3) putting the loaded initial magnet into a discharge plasma device, and carrying out grain boundary diffusion by using discharge plasma heating to raise the temperature, thereby obtaining the final magnet. By controlling the current, the plasma, the pressure and the like in the spark plasma sintering process, the diffusion coefficient of elements is remarkably increased, and the diffusion depth of the elements is increased. According to the grain boundary diffusion rare earth permanent magnet material prepared by the method, the magnetic performance is increased more remarkably, the grain boundary diffusion process can be suitable for large magnets and is not limited by the thickness of the magnets, and the industrialproduction and market requirements are met.

Description

technical field [0001] The present invention relates to the field of permanent magnets, in particular to a grain boundary diffusion method suitable for bulk rare earth permanent magnet materials. Background technique [0002] NdFeB has excellent comprehensive magnetic properties and is widely used in the fields of energy, information, transportation and national defense. It is the most important rare earth functional material and one of the key basic materials of the national economy. However, the temperature stability of sintered NdFeB is poor, and the working temperature is usually lower than 100°C, which greatly limits the applications of electric vehicles, wind power and aerospace. At present, the use of cheap and high-abundance rare earth La / Ce / Y to replace expensive Nd / Pr / Dy / Tb has greatly reduced the cost of raw materials for rare earth permanent magnets, and has attracted widespread attention at home and abroad. However, the intrinsic magnetism of the 2:14:1 phase f...

AI Technical Summary

Problems solved by technology

However, limited by the depth of element diffusion, the ordinary grain boundary diffusion process is only suitable for magnets with a thickness less than 5mm, so the large-scale application is limited