Grain boundary phase-reconstructed high-corrosion resistance Sintered NdFeB magnet and preparation method thereof

A NdFeB, high corrosion resistance technology, applied in the direction of magnetic objects, inductance/transformer/magnet manufacturing, magnetic materials, etc., can solve the problems of increased process, short corrosion resistance time, hydrogen embrittlement, etc., to improve intrinsic resistance Corrosion resistance, high intrinsic corrosion resistance, simple process effect

Active Publication Date: 2008-12-10
ZHEJIANG UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the anti-corrosion problem of magnets has not been fundamentally solved. Various protection methods have different defects. For example, the coating of organic coatings on the surface of magnets has requirements for the working environment, and the corrosion resistance time is not long; during aqueous electroplating, neodymium is easily oxidized and Hydrogen exists in the coating to cause hydrogen embrittlement, etc.
Moreover, the method of using coating as corrosion protection not only increases the process but also increases the cost. In view of the above problems, the current research focuses on exploring a method that can completely improve the corrosion resistance.

Method used

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  • Grain boundary phase-reconstructed high-corrosion resistance Sintered NdFeB magnet and preparation method thereof
  • Grain boundary phase-reconstructed high-corrosion resistance Sintered NdFeB magnet and preparation method thereof
  • Grain boundary phase-reconstructed high-corrosion resistance Sintered NdFeB magnet and preparation method thereof

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Experimental program
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Effect test

Embodiment 1

[0017] 1) Redesign of grain boundary phase alloy composition, the composition is Nd 19 co 1 Cu 13.4 Al 66.6 (at%);

[0018] 2) The main phase alloy and the reconstructed grain boundary phase alloy were prepared separately. The main phase alloy is made of NdFeB ingot alloy by casting process, and its composition is Nd 13.12 Fe 80.69 B 5.73 (Dy 0.22 Ga 0.24 )(at%), reconstructed grain boundary phase alloy Nd 19 co 1 Cu 13.4 Al 66.6 (at%) The quick quenching strip is made by the quick quenching process;

[0019] 3) Powder the main phase alloy and the reconstructed grain boundary phase alloy separately. The primary crushing is carried out by the jaw crusher, the secondary crushing is carried out by the secondary crusher, and then the powders with an average particle diameter of 4 μm and 2 μm are respectively made into powders by jet mills under the protection of nitrogen;

[0020] 4) Evenly mix the reconstituted grain boundary phase alloy powder with the main phase a...

Embodiment 2

[0028] 1) Redesign of grain boundary phase alloy composition, the composition is Nd 12.84 Dy 7.16 Si 3 Zr 1.5 Cu 10.8 Zn 34.2 Ga 30.5 (at%);

[0029] 2) The main phase alloy and the reconstructed grain boundary phase alloy were prepared separately. The main phase alloy is made of NdFeB flakes by quick-setting stripping process, and its composition is Nd 12.2 Fe 80.15 B 5.9 (Tb 0.31 co 1.24 Nb 0.2 )(at%), reconstructed grain boundary phase alloy Nd 12.84 Dy 7.16 Si 3 Zr 1.5 Cu 10.8 Zn 34.2 Ga 30.5 (at%) Ingot alloy made by casting process;

[0030] 3) Powder the main phase alloy and the reconstructed grain boundary phase alloy separately. The primary crushing is carried out by the jaw crusher, the secondary crushing is carried out by the secondary crusher, and then the powders with an average particle diameter of 3.5 μm and 1 μm are respectively made by ball milling under the protection of petroleum ether;

[0031] 4) Evenly mix the reconstituted grain bounda...

Embodiment 3

[0039] 1) Redesign of grain boundary phase alloy composition, the composition is Nd 16 Yb 1 Tb 3 Fe 18.7 co 31.3 Mg 9.7 sn 4.4 Al 15.9 (at%);

[0040] 2) The main phase alloy and the reconstructed grain boundary phase alloy were prepared separately. Both of them are made of NdFeB flakes by using the quick-setting stripping process, and their components are Nd 14.33 Fe 78.91 B 6 (Ga 0.36 Cu 0.2 Zr 0.2 )(at%) and Nd 16 Yb 1 Tb 3 Fe 18.7 co 31.3 Mg 9.7 sn 4.4 Al 15.9 (at%);

[0041] 3) Powder the main phase alloy and the reconstructed grain boundary phase alloy separately. Direct crushing by hydrogen explosion method, saturated hydrogen absorption at room temperature, and then dehydrogenation at 520°C for 8 hours to make hydrogen explosion powder, and finally make powders with average particle diameters of 4.3 μm and 2 μm respectively by jet mill under nitrogen protection;

[0042] 4) Evenly mix the reconstituted grain boundary phase alloy powder with the m...

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Abstract

The invention discloses a sintered Nd-Fe-B magnet with high corrosion resistance and the grain boundary reconstruction and a preparation method thereof. The composition of the invention is that: NdeFe100-e-f-gBfMg, wherein, e is greater than or equal to 6 and equal to or less than 24, f is greater than or equal to 5. 6 and equal to or less than 7, g is greater than or equal to 0.03 and equal to or less than 8, M is one or some of elements Dy, Tb, Pr, Sm, Yb, La, Co, Ni, Cr, Nb, Ta, Zr, Si, Ti, Mo, W, V, Ca, Mg, Cu, Al, Zn, Ga, Bi, Sn and In; The method is that: main phrase alloy and reconstructed grain boundary phase alloy are respectively pulverized and mixed uniformly; the powder mixture is pressed to a mould in the magnetic field, and fabricated into a sintering magnet in a high vacuum sintering furnace. By the reconstruction of the grain boundary phase composition, the invention can obtain the grain boundary phase alloy with low melting point and high electrode potential, decrease the potential difference between the main phase and the grain boundary phase on the basis of ensuring the magnetic properties, promote the intrinsic corrosion resistance of magnet, and has the advantages of simple process, low cost and being suitable for the batch production. Therefore, by combining the grain boundary reconstruction and double alloy method, the sintered Nd-Fe-B magnet with high intrinsic corrosion resistance can be prepared.

Description

technical field [0001] The invention relates to a sintered NdFeB magnet with high corrosion resistance and restructured grain boundary phase and a preparation method thereof. Background technique [0002] Sintered NdFeB permanent magnet material is the most magnetic permanent magnet at present, with excellent characteristics such as high magnetic energy product and high cost performance. Since the invention of NdFeB-based rare earth permanent magnet in Japan in 1983, it has developed rapidly. The world's total output It has jumped from less than 1 ton in that year to nearly 50,000 tons in 2006. It is the most important permanent magnet material at present and in the future. It plays an increasingly important role in the fields of automation technology and healthcare technology, and has become an important material basis for modern science and technology and people's lives. [0003] The main magnetic technical performance index of Nd-Fe-B magnet is remanence B r , coercive ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01F1/057H01F1/08H01F41/02B22F3/12
Inventor 严密崔熙贵周向志
Owner ZHEJIANG UNIV
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