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Grain boundary diffusion method for heavy rare earth elements of sintered neodymium-iron-boron magnet

A heavy rare earth element and grain boundary diffusion technology, applied in the direction of magnetic objects, magnetic materials, electrical components, etc., can solve the problems of shallow diffusion depth, limit the magnetic energy product of magnets, and shallow diffusion depth of heavy rare earth elements, and improve the diffusion uniformity. , the effect of increasing the depth of diffusion

Active Publication Date: 2020-07-10
JIANGSU UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The grain boundary phase with low melting point of sintered NdFeB magnet is the diffusion channel of heavy rare earth element Dy/Tb, but because the grain boundary phase of sintered NdFeB magnet is less and the continuity is poor, the diffusion depth of heavy rare earth element is generally shallow , the size of the magnet with diffusion treatment generally does not exceed 4mm
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Method used

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  • Grain boundary diffusion method for heavy rare earth elements of sintered neodymium-iron-boron magnet
  • Grain boundary diffusion method for heavy rare earth elements of sintered neodymium-iron-boron magnet
  • Grain boundary diffusion method for heavy rare earth elements of sintered neodymium-iron-boron magnet

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Experimental program
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Embodiment 1

[0023] A sintered NdFeB magnet heavy rare earth element grain boundary diffusion method, specifically comprising the following steps:

[0024] Step 1: Cut the N52 (industrial grade) magnet into 10×10×5(c-axis)mm 3 , use sandpaper to polish off the oxide layer on the surface of the magnet;

[0025] Step 2: Add Nd 70 Cu 30 The alloy powder is coated on the surface of the magnet obtained in step 1, and then diffused at 600°C for 3 hours, and then cooled to room temperature with the furnace after diffusion;

[0026] Step 3: Sand the magnet obtained in Step 2 until the surface is clean, and then coat the surface with DyF 3 powder, and then diffused at 850°C for 5 hours, and cooled to room temperature with the furnace after diffusion;

[0027] Step 4: Anneal the magnet obtained in Step 3 at a low temperature of 500° C. for 2 hours, and cool down to room temperature with the furnace after annealing.

[0028] Steps 2, 3, and 4 are carried out in a diffusion furnace, and the vacuu...

Embodiment 2

[0030] A sintered NdFeB magnet heavy rare earth element grain boundary diffusion method, specifically comprising the following steps:

[0031] Step 1: Cut the N52 (industrial grade) magnet into 10×10×5(c-axis)mm 3 , use sandpaper to polish off the oxide layer on the surface of the magnet;

[0032] Step 2: Put Pr 70 Cu 30 The alloy powder is coated on the surface of the magnet obtained in step 1, and then diffused at 750°C for 1 hour, and then cooled to room temperature with the furnace after diffusion;

[0033] Step 3: Polish the magnet obtained in Step 2 with sandpaper until the surface is clean, and then coat the surface with TbF 3 powder, and then diffused at 800°C for 8 hours, and cooled to room temperature with the furnace after diffusion;

[0034] Step 4: Anneal the magnet obtained in Step 3 at a low temperature of 450° C. for 4 hours, and cool down to room temperature with the furnace after annealing.

[0035] Steps 2, 3, and 4 are carried out in a diffusion furnac...

Embodiment 3

[0037] A sintered NdFeB magnet heavy rare earth element grain boundary diffusion method, specifically comprising the following steps:

[0038] Step 1: Cut the N52 (industrial grade) magnet into 10×10×5(c-axis)mm 3 , use sandpaper to polish off the oxide layer on the surface of the magnet;

[0039] Step 2: Put Pr 70 Cu 30 The alloy powder is coated on the surface of the magnet obtained in step 1, and then diffused at 500°C for 6 hours, and then cooled to room temperature with the furnace after diffusion;

[0040] Step 3: Polish the magnet obtained in Step 2 with sandpaper until the surface is clean, and then coat the surface with TbF 3 powder, and then diffused at 900°C for 4 hours, and cooled to room temperature with the furnace after diffusion;

[0041] Step 4: Anneal the magnet obtained in Step 3 at a low temperature of 500° C. for 2 hours, and cool down to room temperature with the furnace after annealing.

[0042] Steps 2, 3, and 4 are carried out in a diffusion furna...

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Abstract

The invention discloses a grain boundary diffusion method for heavy rare earth elements of a sintered neodymium-iron-boron magnet. The method comprises the following steps: low-temperature grain boundary diffusion treatment is performed on a magnet by using low-melting-point alloy powder without heavy rare earth elements, the molten low-melting-point alloy diffuses and permeates into the magnet along the grain boundary, and the diffused magnet has a continuous low-melting-point grain boundary phase; high-temperature grain boundary diffusion treatment is performed on the magnet by using compound powder rich in heavy rare earth elements, and the heavy rare earth elements diffuse into the magnet along a continuous grain boundary phase to form a shell structure rich in the heavy rare earth elements at the edge of matrix grains; and finally, annealing treatment is performed on the magnet to optimize grain boundary phase distribution. Through the two-step diffusion method, compared with traditional one-step grain boundary diffusion, the diffusion depth and the diffusion uniformity of the heavy rare earth elements are improved, a thick magnet can be subjected to diffusion treatment, and the coercive force and the demagnetization curve squareness of the diffused magnet are remarkably superior to the traditional one-step grain boundary diffusion effect.

Description

technical field [0001] The invention relates to a grain boundary diffusion method of a sintered NdFeB magnet, in particular to a method for improving the grain boundary diffusion of a heavy rare earth element in a sintered NdFeB magnet. Background technique [0002] Permanent magnetic materials can realize the mutual conversion of mechanical energy and electrical energy by using the magnetic field in the air gap, and have been widely used in aerospace, power electronics, medical equipment, transportation and other fields. Rare earth permanent magnet NdFeB material is a kind of permanent magnet material with the highest magnetic energy product at present. The high magnetic energy density meets the development needs of equipment miniaturization. Has occupied two-thirds of the permanent magnet material market. [0003] In recent years, with the vigorous development of the high-efficiency permanent magnet motor industry, the demand for high-coercivity NdFeB magnets that can mee...

Claims

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Application Information

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IPC IPC(8): H01F41/02H01F1/057
CPCH01F41/0293H01F1/0577
Inventor 陈夫刚陈洪美王晓丽杨志东
Owner JIANGSU UNIV OF SCI & TECH