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Method for improving corrosion resistance of neodymium-iron-boron magnet by carrying out grain boundary diffusion on Al-Cu alloy

A technology of grain boundary diffusion and neodymium iron boron, applied in the direction of magnetic materials, magnetic objects, permanent magnet manufacturing, etc., can solve the problem of damaging the magnetic properties of magnets, and achieve the effect of reducing magnetic properties

Inactive Publication Date: 2017-05-31
SOUTH CHINA UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, this method often dissolves some elements in the main phase, which damages the magnetic properties of the magnet.

Method used

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  • Method for improving corrosion resistance of neodymium-iron-boron magnet by carrying out grain boundary diffusion on Al-Cu alloy
  • Method for improving corrosion resistance of neodymium-iron-boron magnet by carrying out grain boundary diffusion on Al-Cu alloy

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0028] Example 1: 48SH magnet surface coated with Al 82.9 Cu 17.1 (atomic percent) powder grain boundary diffusion heat treatment

[0029] Select 48SH commercial sintered NdFeB magnets and process them into a square sample with a size of 4×4×4mm, which is recorded as sample No. 1.

[0030] According to the alloy composition ratio Al 82.9 Cu 17.1 (Atomic percentage) Weigh Al and Cu with a purity greater than 99.99%, put Al and Cu in an electric arc furnace, and evacuate to 5×10 -3 Pa, first melt the oxygen-absorbing Ti block to exhaust the oxygen in the residual cavity, and then repeatedly smelt each sample 4 times to ensure that the components are evenly distributed.

[0031] The smelted button-shaped ingot is polished with a grinding wheel, and then polished with fine sandpaper to remove the surface oxide skin, and ultrasonically cleaned in alcohol. Use pliers to roughly break into small pieces, according to the ball-to-material ratio of 10:1, the rotation speed is 300r / ...

Embodiment 2

[0033] Example 2: 48SH magnet surface coated with Al 89 Cu 11 (atomic percent) powder grain boundary diffusion heat treatment

[0034] Select 48SH commercial sintered NdFeB magnets and process them into a square sample with a size of 4×4×4mm, which is recorded as sample No. 1.

[0035] According to the alloy composition ratio Al 89 Cu 11 (Atomic percentage) Weigh Al and Cu with a purity greater than 99.99%, put Al and Cu in an electric arc furnace, and evacuate to 5×10 -3 Pa, first melt the oxygen-absorbing Ti block to exhaust the oxygen in the residual cavity, and then repeatedly smelt each sample 5 times to ensure that the components are evenly distributed.

[0036] The smelted button-shaped ingot is polished with a grinding wheel, and then polished with fine sandpaper to remove the surface oxide skin, and ultrasonically cleaned in alcohol. Use pliers to roughly break into small pieces, according to the ball-to-material ratio of 10:1, the rotation speed is 200r / min, an...

Embodiment 3

[0038] Example 3: 48SH magnet surface coated with Al 75 Cu 25 (atomic percent) powder grain boundary diffusion heat treatment

[0039] Select 48SH commercial sintered NdFeB magnets and process them into a square sample with a size of 4×4×4mm, which is recorded as sample No. 1.

[0040] According to the alloy composition ratio Al 75 Cu 25 (Atomic percentage) Weigh Al and Cu with a purity greater than 99.99%, put Al and Cu in an electric arc furnace, and evacuate to 5×10 -3 Pa, first melt the oxygen-absorbing Ti block to exhaust the oxygen in the residual cavity, and then repeatedly smelt each sample 4 times to ensure that the components are evenly distributed.

[0041]The smelted button-shaped ingot is polished with a grinding wheel, and then polished with fine sandpaper to remove the surface oxide skin, and ultrasonically cleaned in alcohol. Use pliers to roughly break into small pieces, according to the ball-to-material ratio of 10:1, the speed is 400r / min, and the ball...

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Abstract

The invention discloses a method for improving the corrosion resistance of neodymium-iron-boron magnet by carrying out grain boundary diffusion on Al-Cu alloy, belonging to the field of rare earth magnetic materials. According to the method, an Al-Cu alloy ordinary ingot which has a low melting point and high potential is directly used as a surface diffusion source of the neodymium-iron-boron magnet after being coarsely crushed and ball-milled, and an Al-Cu-rich thin layer is formed at the crystal boundary of the neodymium-iron-boron magnet after diffusing heat treatment and annealing heat treatment are carried out, so that the neodymium-iron-boron magnet with high corrosion resistance is obtained. According to the method, Al-Cu alloy is taken as the diffusion source, thus avoiding the phenomenon that the residual magnetism of the magnet is reduced since Al and Cu elements are not directly added into the ingot, and the non-magnetic Al and Cu enter a principal phase so as to generate a magnetic dilution effect; the corrosion resistance and magnetic property of the magnet also can be improved since the grain boundary diffusion can improve the chemical stability of a grain boundary phase, optimize a microstructure, improve the distribution of the grain boundary phase, and increases the density of the magnet.

Description

technical field [0001] The invention belongs to the field of rare earth permanent magnet materials, in particular to a method for improving the corrosion resistance of NdFeB magnets by grain boundary diffusion Al-Cu alloys. [0002] technical background [0003] NdFeB magnets are permanent magnet materials with the strongest comprehensive magnetic properties at room temperature in the world today, with high remanence, high coercive force and high magnetic energy product. As a new generation of rare earth permanent magnet materials, NdFeB magnets are widely used in computer technology, transportation, aerospace military industry, automation technology, instrument technology, microwave communication technology, medical treatment, wind power generation and other fields. NdFeB magnets can be divided into sintered NdFeB magnets and bonded NdFeB magnets. Among them, sintered NdFeB magnets have relatively good magnetic properties and are the most widely used. Low corrosion resistan...

Claims

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Application Information

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IPC IPC(8): H01F41/02H01F1/057C23C10/26
CPCH01F41/026C23C10/26H01F1/0571
Inventor 余红雅邓晶曾德长郑志刚
Owner SOUTH CHINA UNIV OF TECH
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