Method for preparing high-coercivity neodymium-iron-boron magnet through grain boundary diffusion

A technology with high coercivity and grain boundary diffusion, which is applied in the manufacture of magnetic objects, magnetic materials, inductors/transformers/magnets, etc. Diffusion process and uniformity of magnet structure and properties, suitable for mass continuous production, high bonding strength

Inactive Publication Date: 2017-06-23
UNIV OF SCI & TECH BEIJING
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

In the actual preparation process, the adhesion ability of the brushing method is poor. If you want to increase the adhesion ability by spraying, the powder particle size must be below 10 microns. For alloys, it is quite difficult to prepare corresponding low-oxygen powders.
Due to the high vapor pressure of dysprosium, vapors tend to adher...

Method used

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  • Method for preparing high-coercivity neodymium-iron-boron magnet through grain boundary diffusion

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0021] Example 1: Sintered NdFeB magnets are hot dipped with Pr 68 Cu 32 Preparation of High Coercive Force Magnet by Post-Grain Boundary Diffusion Heat Treatment of Alloy

[0022] (1) Clean the surface of the NdFeB magnet;

[0023] (2) Vacuum melting Pr 68 Cu 32 alloy (atomic fraction);

[0024] (3) Pr 68 Cu 32 The alloy is heated to about 500°C in a vacuum plating tank to melt the alloy into a uniform melt;

[0025] (4) After the magnet is vacuum preheated at about 500°C for about 1-3 minutes, it is immersed in the alloy melt for hot-dip plating, and then cooled after taking it out;

[0026] (5) The magnet is subjected to diffusion and annealing heat treatment in a vacuum furnace. The diffusion heat treatment temperature is 900° C. for 2 hours, and the annealing temperature range is 480° C. for 2 hours.

[0027] (6) After surface treatment, the desired high coercivity NdFeB magnets are obtained.

Embodiment 2

[0028] Example 2: Sintered NdFeB magnets are hot dipped with Nd 60 Dy 20 Al 20 Preparation of High Coercive Force Magnet by Post-Grain Boundary Diffusion Heat Treatment of Alloy

[0029] (1) Clean the surface of the NdFeB magnet;

[0030] (2) Vacuum melting Nd 60 Dy 20 Al 20 alloy (atomic fraction);

[0031] (3) Nd 60 Dy 20 Al 20 The alloy is heated to about 680°C in a vacuum plating tank to melt the alloy into a uniform melt;

[0032] (4) After the magnet is vacuum preheated at about 680°C for about 1-3 minutes, it is immersed in the alloy melt for hot-dip plating, and then cooled after taking it out;

[0033] (5) The magnet is subjected to diffusion and annealing heat treatment in a vacuum furnace. The diffusion heat treatment temperature is 900°C for 2 hours, and the annealing temperature range is 500°C for 2 hours.

[0034] (6) After surface treatment, the desired high coercivity NdFeB magnets are obtained.

Embodiment 3

[0035] Example 3: Hot dip coating of sintered NdFeB magnets with Al 70 Cu 30 Preparation of High Coercive Force Magnet by Post-Grain Boundary Diffusion Heat Treatment of Alloy

[0036] (1) Clean the surface of the NdFeB magnet;

[0037] (2) Vacuum melting Al 70 Cu 30 alloy (atomic fraction);

[0038] (3) Al 70 Cu 30 The alloy is heated to about 640°C in a vacuum plating tank to melt the alloy into a uniform melt;

[0039] (4) After the magnet is vacuum preheated at about 640°C for about 1-3 minutes, it is immersed in the alloy melt for hot-dip plating, and then cooled after taking it out;

[0040] (5) The magnet is subjected to diffusion and annealing heat treatment in a vacuum furnace. The diffusion heat treatment temperature is 900°C for 2 hours, and the annealing temperature range is 500°C for 2 hours.

[0041] (6) After surface treatment, the desired high coercivity NdFeB magnets are obtained.

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Abstract

The invention discloses a method for preparing a high-coercivity neodymium-iron-boron magnet through grain boundary diffusion, and belongs to the field of magnetic materials. Low-melting-point metal is one of Ga, Zn and Sn, low-melting-point alloy is prepared from R-M, R is one or more of La, Ce, Pr, Nd, Gd, Tb, Dy, Ho and Y, and M is one or more of Cu, Al, Ga, Sn and Ag. The method comprises the process steps that the surface of a neodymium-iron-boron magnet is cleaned firstly, then the magnet is subjected to vacuum preheating, and the magnet is placed in a vacuum melting metal or alloy solution for hot dip coating to achieve surface coating; finally, the neodymium-iron-boron magnet obtained after hot dip coating is subjected to diffusing heat treatment and subsequent annealing treatment, the boundary structure and grain boundary phase distribution of the magnet are improved, and the needed high-coercivity neodymium-iron-boron magnet is obtained. The magnet surface coating is even and high in binding strength, and uniformity of the grain boundary diffusion process and the structure and performance of the magnet are promoted; meanwhile, the thickness of an attached layer on the surface of the magnet can be flexibly controlled by controlling dip coating time and taking-out speed, and waste of diffusion source metal or alloy is avoided; the heat dip coating process is continuous, fast and suitable for volume continuous production.

Description

technical field [0001] The invention belongs to the field of magnetic materials, and particularly provides a method for preparing a high-coercivity neodymium-iron-boron magnet by grain boundary diffusion. Background technique [0002] The global attention and promotion of new energy vehicles and wind power industries will have a major impact on high-end rare earth permanent magnets. Both direct-drive permanent magnet units for wind power generation and drive motors for new energy vehicles will use high-coercivity sintered NdFeB in large quantities. magnet. As we all know, in order to increase the coercive force of NdFeB sintered magnets, it is a very effective method to partially replace Nd in the magnets with heavy rare earth elements such as Dy / Tb. However, if the traditional alloying method is used, a large amount of Dy / Tb needs to be added to achieve high coercive force, which not only reduces the remanence and magnetic energy product, but also increases the production ...

Claims

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Application Information

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IPC IPC(8): H01F41/02H01F1/057
CPCH01F41/0293H01F1/057H01F41/0253
Inventor 包小倩高学绪汤明辉牟星卢克超
Owner UNIV OF SCI & TECH BEIJING
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