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Method for improving sintered nd-fe-b magnet crystal boundary

A technology of NdFeB and magnets, which is applied in the manufacture of magnetic objects, magnetic materials, inductors/transformers/magnets, etc., can solve the problems of limited doping phase effect, achieve the effect of weakening the thickness of lattice distortion and increasing the coercive force

Active Publication Date: 2015-12-30
ZHEJIANG DONGYANG DMEGC RARE EARTH MAGNET CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

At present, the mixed phase is mainly a single phase, so the role played by the mixed phase is relatively limited.

Method used

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  • Method for improving sintered nd-fe-b magnet crystal boundary

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0028] Cu powder with a particle size of about 3 microns is placed in the HF solution and stirred to make the surface fully react with HF and generate CuF on the surface 2 layer, separated by filtration, and dried at 200°C under vacuum. Using double alloy method and (Pr 0.25 Nd 0.75 ) 2.03 Fe 14.1 Nb 0.2 co 0.2 Al 0.3 B 1 The magnet powders are mixed, the doping amount is 0.5wt%, and they are fully mixed and pressed into blocks. After sintering and annealing, the properties are: Br=13.52Gs, Hcj=15.5kOe, (BH) max = 44.3 MOeGs.

Embodiment 2

[0030] Put metal Ga powder (average particle size is about 2.1 microns) in F 2 In the mixed gas with argon, F in the mixed gas 2 5% of volume fraction. The surface of the powder was fully reacted by gas flow for 2.5 hours. Incorporated into (Pr 0.25 Nd 0.75 ) 2.03 Fe 14.1 Nb 0.2 co 0.2 Al 0.3 B 1 In the magnet powder, the doping amount is 1wt%, and it is pressed into a block after being fully mixed. After sintering and annealing, the properties are: Br=13.67Gs, Hcj=16.3kOe, (BH) max = 44.9 MOeGs.

Embodiment 3

[0032] The metal Dy / Fe (mass ratio is 4:1) block is subjected to hydrogen breaking and jet milling to obtain Dy / Fe powder (average particle size is about 3.0 microns), which is placed in F 2 In the mixed gas with argon, F in the mixed gas 2 5% of volume fraction. The surface of the powder was fully reacted by gas flow for 1.5 hours. Incorporated into (Pr 0.25 Nd 0.75 ) 2.03 Fe 14.1 Nb 0.2 co 0.2 Al 0.3 B 1 In the magnet powder, the doping amount is 2wt%, and it is pressed into a block after being fully mixed. After sintering and annealing, the properties are: Br=13.56Gs, Hcj=17.2kOe, (BH) max = 44.7 MOeGs.

[0033] Through comparative examples, Example 1, Example 2 and Example 3, it is an effective method to improve the magnetic properties of NdFeB by using the double alloy method to properly add metal fluoride in the grain boundary, and effectively improve the magnetic properties of sintered NdFeB. Coercivity of boron magnets.

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Abstract

The invention discloses a method for improving the sintered nd-fe-b magnet crystal boundary. The method includes the following specific operation steps that 1, nd-fe-b powder is prepared through a conventional method; 2, a sort of metal or alloy powder M is collected, and surface fluorinated treatment is conducted on the powder M; 3, the surface-fluorinated powder is doped into the nd-fe-b powder through a double-alloy method; 4, the evenly-mixed powder is sintered after being formed and pressed, a sintered sample is then subjected to annealing treatment, and accordingly a sintered nd-fe-b magnet is obtained. The method has the advantages that on one hand, F elements are aptly added in the crystal boundary, accordingly, an ordered NdOF phase can be generated, and thus the coercivity of the magnet is improved; on the other hand, the exchange coupling action between crystals is weakened by adding the F elements; furthermore, the lattice deformation thickness can be effectively reduced by adding the F elements, and the coercivity of the magnet can be effectively improved as well.

Description

technical field [0001] The invention relates to the related technical field of sintered NdFeB magnets, in particular to a method for improving the grain boundaries of sintered NdFeB magnets. Background technique [0002] The oxygen content in sintered NdFeB magnets has an important impact on the performance of the magnet. When the NdFeB magnet contains too much oxygen, the magnetic properties of the material will be significantly reduced. The main reason is that oxygen will oxidize the grain boundary phase. Neodymium phase, causing the neodymium-rich phase to shrink and concentrate in the triangular connection area of ​​the grain boundary during sintering, instead of being evenly distributed among the crystal planes. But this does not mean that the lower the oxygen content of the magnet in NdFeB, the better its performance. Proper oxidation can effectively improve the coercive force of the magnet, because the Nd-rich phase oxidized at the grain boundary edge provides a pinn...

Claims

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Application Information

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IPC IPC(8): H01F41/02H01F1/057B22F1/00
Inventor 王成胜洪群峰章晓峰
Owner ZHEJIANG DONGYANG DMEGC RARE EARTH MAGNET CO LTD
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