Anisotropic rare-earth magnet light wave microwave sintering method

Abstract

The invention relates to an anisotropic rare-earth magnet light wave microwave sintering method. Pressed and formed R-Fe-B (R is at least one of rare earth elements) series anisotropic rare-earth magnet green bodies after the completion of magnetic field orientation are placed in a light wave microwave oven, and the combination energy of light waves and microwaves are used for sintering. The frequency of microwaves is 500 MHz to 250 GHz, the atmosphere is vacuum or inert gas, the power of the light waves and the microwaves is proportionally controlled as required, and the sintering temperature is 980 DEG C to 1200 DEG C. The respective heating characteristics of the light waves and the microwaves are used, the heating speed is high, and the temperature gradient in the magnet green bodies is further reduced in sintering; the zero gradient even heating in a larger area in a sintered material can be realized, the grain growth inside the material is even and fine, and the magnetic performance of the finished product can be increased; meanwhile, the invention has the characteristics of low thermal stress, less cracking and deformation, energy saving, environment protection and the like.

Description

technical field [0001] The invention relates to a sintering method of a rare-earth magnet, in particular to a light-wave microwave sintering method of an anisotropic rare-earth magnet. Background technique [0002] Magnetic materials are widely used in the construction of the national economy, and rare earth anisotropic sintered magnets represented by anisotropic NdFeB (neodymium iron boron) occupy an irreplaceable position due to their high magnetic properties. However, the traditional magnet sintering method has some inherent defects, which affect its further development and application. The traditional magnet sintering method is to rely on the heating element to transfer heat energy to the magnet body through convection, conduction or radiation, so that the temperature of the magnet body reaches the sintering temperature, thereby completing sintering. In this sintering method, the heat is transferred from the outside to the inside, the sintering time is long, and the ene...

AI Technical Summary

Problems solved by technology

Uneven heating will lead to uneven growth of grains inside the material, and abnormal growth of grains, which will not only affect the magnetic properties of the finished product, but also cause large deformation of the sintered product, poor shape and dimension accuracy, and easy cracking, etc. It causes the pass rate of the product to decrease and increases the production cost; in addition, there is a method of using spark plasma sintering, which (SPS technology) is a pressure sintering method using DC pulse current energization sintering. The discharge plasma generated instantaneously by the input of DC pulse current makes each particle inside the sintered body evenly generate Joule heat and activates the surface of the particle, and realizes sintering while pressurizing

The sintering is completed instantaneously, but a glow discharge will be generated between the magnet particles, resulting in excessive sintering, which will also increase the grain diameter and affect the magnetic properties of the finished product; there is also a microwave sintering method, in which the microwave is heating the magnet body At this time, the internal temperature of the green body is higher than the peripheral temperature, and there is also a temperature gradient. Although it is improved compared with the traditional sintering method, there are still some problems of uneven heating of the green body, and there will still be a certain amount of deformation. Poor, easy to crack, and uneven growth of internal grains occurs