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A method for preparing high coercivity anisotropic nanocrystalline NdFeB permanent magnet

An anisotropic, high coercivity technology, applied in the field of thermally deformed NdFeB rare earth permanent magnets, to achieve the effects of reduced remanence, good magnetic properties, and fine and uniform grains

Active Publication Date: 2016-08-24
BEIJING UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

At present, the laboratory has been able to prepare NdFeB magnets with a maximum energy product of more than 50MGOe by hot pressing / hot deformation methods, but has not yet used TbH 3 Preparation of NdFeB magnets by SPS hot pressing / hot deformation after mixing with NdFeB powder

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0023] (1) Prepare and collect TbH by hydrogen arc nanopowder preparation system 3 Nano powder, the particle size is 10-50nm;

[0024] (2) Under the protection of argon, 0.5wt.% TbH 3 The nanometer powder is added in the NdFeB magnetic powder (MQ powder), utilizes mixer to mix evenly;

[0025] (3) Hot pressing stage: put the mixed magnetic powder into a cemented carbide mold, and use discharge plasma technology to hot press under the conditions of vacuum, 300MPa, and 670°C to obtain an isotropic nanocrystalline magnet;

[0026] (4) Thermal deformation stage: Put an isotropic magnet into a graphite mold with a preset size, and use spark plasma sintering technology to thermally deform under the conditions of vacuum, 30MPa, and 770°C to obtain massive anisotropic nanocrystals magnet;

[0027] (5) Put the hot-pressed / hot-deformed anisotropic magnet at 1×10 -3 Anneal at 650°C for 5h under Pa vacuum.

Embodiment 2

[0034] (1) Prepare and collect TbH by hydrogen arc nanopowder preparation system 3 Nano powder, the particle size is 10-50nm;

[0035] (2) Under the protection of argon, 0.7wt.% TbH 3 The nanometer powder is added in the NdFeB magnetic powder (MQ powder), utilizes mixer to mix evenly;

[0036] (3) Hot pressing stage: put the mixed magnetic powder into a cemented carbide mold, and use spark plasma sintering technology to hot press under the conditions of vacuum, 300MPa, and 660°C to obtain an isotropic magnet;

[0037] (4) Thermal deformation stage: Put the isotropic magnet into a graphite mold with a preset size, and use spark plasma sintering technology to thermally deform under the conditions of vacuum, 30MPa, and 760°C to obtain a block-shaped anisotropic magnet;

[0038] (5) Anisotropic magnets that are hot-pressed and deformed at 1×10 -3 P a Annealed at 650 °C for 5 h in a vacuum environment.

[0039]

Embodiment 3

[0041] (1) Prepare and collect TbH by hydrogen arc nanopowder preparation system 3 Nano powder, the particle size is 10-50nm;

[0042] (2) Under the protection of argon, 1.0wt.% TbH 3 The nanometer powder is added in the NdFeB magnetic powder (MQ powder), utilizes mixer to mix evenly;

[0043] (3) Hot pressing stage: put the mixed magnetic powder into a cemented carbide mold, and use spark plasma sintering technology to hot press under the conditions of vacuum, 300MPa, and 660°C to obtain an isotropic magnet;

[0044] (4) Thermal deformation stage: Put the isotropic magnet into a graphite mold with a preset size, and use spark plasma sintering technology to thermally deform under the conditions of vacuum, 30MPa, and 760°C to obtain a block-shaped anisotropic magnet;

[0045] (5) Anisotropic magnets that are hot-pressed and deformed at 1×10 -3 Annealed at 650°C for 5h in a vacuum environment of Pa.

[0046]

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Abstract

The invention discloses a method for preparing a high-coercivity anisotropic nanocrystalline NdFeB permanent magnet, which belongs to the technical field of magnetic materials. The present invention adopts spark plasma sintering technology, NdFeB powder and TbH 3 An anisotropic NdFeB magnet is obtained by hot pressing and thermal deformation of the mixture of nanometer powder, and then an anisotropic nanocrystalline NdFeB magnet with high coercive force is obtained by heat treatment. When TbH x When the addition amount is 0.7wt.%, after the heat-deformable magnet is annealed at 650°C, the coercivity of the heat-deformable magnet increases by 53.3% and the remanence decreases by 2.2% compared with that of the undoped heat-deformable magnet at the same temperature. Compared with the traditional powder metallurgy process, it has the advantages of less Tb addition, significantly improved coercive force, and less damage to residual magnetism. Moreover, the thermally deformed nanocrystalline NdFeB magnet prepared by spark plasma sintering also has improved coercive force, thermal stability, corrosion resistance and mechanical properties.

Description

technical field [0001] The invention relates to a method for preparing a hot-deformed NdFeB rare-earth permanent magnet with high coercive force doped with heavy rare earth hydride nanoparticles by adopting a discharge plasma technology hot pressing / hot deformation method, and belongs to the technical field of magnetic materials. Background technique [0002] Sintered NdFeB rare earth permanent magnet is the most magnetic permanent magnet material so far. It is widely used in many fields such as electronics, electromechanical, instrumentation and medical treatment. It is the fastest growing permanent magnet material with the best market prospect in the world today. With the rapid development of hybrid vehicles, high-temperature permanent magnets with an operating temperature above 200 °C are required. Therefore, higher requirements are placed on the high-temperature magnetic properties of NdFeB magnets. [0003] The coercive force of ordinary NdFeB magnets drops sharply at h...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01F41/02H01F1/057B22F1/00B22F3/14
Inventor 岳明张东涛王春国路清梅刘卫强吴琼张红国
Owner BEIJING UNIV OF TECH
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