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Method for improving corrosion resistance and coercive force of sintered neodymium-iron-boron magnet

A NdFeB, corrosion-resistant technology, applied in the manufacture of permanent magnets, inductors/transformers/magnets, coatings, etc., can solve the problem of reducing magnet remanence and energy product, poor corrosion resistance and temperature stability. And other problems, to achieve the effect of improving coercive force, shortening heat treatment time, and improving corrosion resistance

Inactive Publication Date: 2018-10-19
BEIJING UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, its poor corrosion resistance and temperature stability severely limit the expansion of its application range. With the development of science and technology, the requirements for the comprehensive performance of NdFeB magnets in various fields are getting higher and higher. Therefore, the development of high comprehensive performance NdFeB magnets become an inevitable trend
[0003] After continuous exploration, it has been found that the corrosion of NdFeB magnets mainly occurs on the grain boundaries. , can improve the corrosion resistance and coercive force of the magnet, but these elements are added during smelting, and will be evenly distributed in the main phase grain Nd 2 Fe 14 B and Nd-rich phase, and they are non-magnetic atoms, will reduce the molecular magnetic moment after entering the main phase, thereby greatly reducing the remanence and energy product of the magnet

Method used

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  • Method for improving corrosion resistance and coercive force of sintered neodymium-iron-boron magnet

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0018] 1) Take a sintered NdFeB magnet with an external dimension of 10mm*10mm*4mm, denoted as A0, and perform surface polishing on it;

[0019] 2) Place an appropriate amount of the pretreated magnet and solid Ga in the crucible;

[0020] 3) Place the crucible in a vacuum heat treatment furnace, heat treatment at 500°C for 0.5h, and the vacuum degree is greater than 10 -2 Pa;

[0021] 4) After the heat treatment, take out the crucible, heat it to 30°C in the air, and then take out the magnet from the molten Ga, and record it as A1;

[0022] 5) Take the original magnet A0 and the magnet A1 that has been infiltrated with Ga, respectively, and polish them on six sides, and then put them in an autoclave at the same time, and perform corrosion at high temperature and high pressure (temperature 121 °C, 2 atmospheres) for 55 hours. , take out the magnet after the corrosion is over, and calculate the weight loss.

[0023] Table 1 Comparison of corrosion resistance between A1 and A...

Embodiment 2

[0029] 1) Take a sintered NdFeB magnet with an external dimension of 10mm*10mm*4mm, denoted as B0, and perform surface polishing on it;

[0030] 2) Place an appropriate amount of the pretreated magnet and solid Ga in the crucible;

[0031] 3) Place the crucible in a vacuum heat treatment furnace, heat treatment at 600°C for 0.5h, and the vacuum degree is greater than 10 -2 Pa;

[0032] 4) After the heat treatment, take out the crucible, heat it to 30°C in the air, and then take out the magnet from the molten Ga, denoted as B1;

[0033] 5) Take the original magnet B0 and the magnet B1 that has been infiltrated with Ga, respectively, and polish six sides of them, and then put them in an autoclave at the same time, and perform high-temperature and high-pressure corrosion (temperature is 121 ° C, 2 atmospheres) for 55 hours. , take out the magnet after the corrosion is over, and calculate the weight loss.

[0034] Table 3 Corrosion resistance comparison between B1 and B0

[00...

Embodiment 3

[0039] 1) Take a sintered NdFeB magnet with an external dimension of 10mm*10mm*4mm, denoted as C0, and perform surface polishing on it;

[0040] 2) Place an appropriate amount of the pretreated magnet and solid Ga in the crucible;

[0041] 3) Place the crucible in a vacuum heat treatment furnace, heat treatment at 400°C for 1 hour, and the vacuum degree is greater than 10 -2 Pa;

[0042] 4) Take out the crucible after the heat treatment, heat it to 30°C in the air, then take out the magnet from the molten Ga, and record it as C1;

[0043] 5) Take the original magnet C0 and the magnet C1 that has been infiltrated with Ga, respectively, and polish them on six sides, and then put them in an autoclave at the same time, and perform high-temperature and high-pressure corrosion (temperature is 121 ° C, 2 atmospheres) for 55 hours. , take out the magnet after the corrosion is over, and calculate the weight loss.

[0044] Table 5 Comparison of corrosion resistance between C1 and C0 ...

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Abstract

The invention provides a method for improving corrosion resistance and coercive force of a sintered neodymium-iron-boron magnet, and belongs to the technical field of magnetic materials. The performance of the magnet is improved by adopting a method that the sintered neodymium-iron-boron magnet is soaked in a liquid gallium solution at a certain temperature. The method particularly comprises the steps that firstly a pretreated sintered neodymium-iron-boron magnet and moderate solid gallium are taken to be placed in a crucible, then the crucible is placed in a vacuum thermal treatment furnace to be heated, wherein the temperature is 400-600 DEG C, the time is 0.5-1 hour, then after the thermal treatment is completed, the crucible is taken out and heated in the air until the temperature is 30 DEG C, then the magnet is taken out from the melted gallium. The corrosion resistance and coercive force of the treated magnet are improved.

Description

technical field [0001] The invention relates to a method for improving the corrosion resistance and coercive force of a sintered NdFeB magnet, belonging to the technical field of magnetic materials. Background technique [0002] NdFeB permanent magnet material is the third generation of permanent magnet material. Since its discovery, it has been called the "Magnetic King" for its excellent magnetic properties. Electronics, wind power generation, aerospace and many other fields. However, its poor corrosion resistance and temperature stability severely limit the expansion of its application range. With the development of science and technology, the requirements for the comprehensive performance of NdFeB magnets in various fields are getting higher and higher. Therefore, it is necessary to develop high comprehensive performance NdFeB magnets. NdFeB magnets have become an inevitable trend. [0003] After continuous exploration, it has been found that the corrosion of NdFeB mag...

Claims

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Application Information

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IPC IPC(8): H01F41/02C23C10/22
CPCC23C10/22H01F41/0253H01F41/026
Inventor 刘卫强李一岳明吴丹张东涛
Owner BEIJING UNIV OF TECH
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