Grain boundary diffusion method for improving diffusion performance of R-T-B magnet

Abstract

The grain boundary diffusion method comprises the steps that the surface of an R-T-B magnet base body is covered with a diffusion source, the diffusion source is heavy rare earth, and the mass of the diffusion source is 0.2%-4% of the mass of the magnet base body; the magnet covered with the diffusion source is subjected to grain boundary diffusion treatment, the diffusion temperature ranges from 800 DEG C to 1000 DEG C, the diffusion time ranges from 1 h to 48 h, and within 1 h to 3 h before diffusion, the absolute vacuum degree is adjusted to be 1.0 * 10 <-3 > Pa to 4.6 * 10 <-3 > Pa; and then the absolute vacuum degree is adjusted to be low vacuum between 3.6 kpa and 7.6 kpa, after grain boundary diffusion, cooling is conducted to the room temperature, then heating is conducted, tempering treatment is conducted, and the R-T-B magnet subjected to grain boundary diffusion is obtained. The Hcj of the magnet can be improved, and the residual magnetism reduction amount can be reduced.

Description

technical field [0001] The invention provides a grain boundary diffusion method for improving the performance of the R-T-B magnet by adjusting the vacuum degree and the diffusion temperature of the diffusion treatment. Background technique [0002] The sintered NdFeB magnet material has high magnetic properties, does not contain rare metal Co, is relatively low in price, has a wide range of applications, and has a long service life, so it has broad development prospects. [0003] However, sintered NdFeB magnets are still in the development stage. First, the magnetic energy product of sintered NdFeB magnets has not yet reached the theoretical limit after nearly 40 years of development. The current magnetic energy product of sintered NdFeB magnets can reach 93% of the theoretical value. Industrial small-batch production and The magnetic energy product obtained in mass production is lower. Secondly, Br is close to the theoretical value, but Hcj is far from the theoretical valu...

AI Technical Summary

Problems solved by technology

[0005] Diffusion technology is a technology that can rapidly increase Hcj in recent years. It has the advantages of low cost, convenient operation, and high cost performance. However, the principle of diffusion technology is that the Nd-rich phase melts and volatilizes at high temperature to form a diffusion channel, and the diffusion source diffuses to the inside through the diffusion channel. , but there is a large amount of volatilization of the Nd-rich phase during the diffusion process, resulting in a substantial increase in Hcj and a substantial decrease in Br, so how to reduce the decrease in Br while increasing Hcj is very critical

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