Method for increasing neodymium-iron-boron permanent magnetic performance and corrosion-resisting performance

A permanent magnet material, neodymium iron boron technology, applied in the direction of inorganic materials, magnetic materials, magnetic objects, etc., can solve the problems of magnetic phase order crystal structure destruction, magnetic performance decline, magnetic performance reduction, etc., to achieve increased magnet density , Improve the stability and improve the corrosion resistance of the magnet

Inactive Publication Date: 2007-03-28
SHANGHAI JIAO TONG UNIV
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Problems solved by technology

[0004] Found through literature search to prior art, L.Schultz, A.M.El-Aziz etc. [Corrosion behavior of Nd-Fe-B permanent magnetic alloys.Materials Science and Engineering A, 267 (1999): 307-313] once in materials science and An article on "Corrosion Behavior of NdFeB Permanent Magnet Materials" was published in Engineering A Journal. The effects of , Mo on the magnetic properties and corrosion resistance were studied and summarized. The results showed that the addition of the above alloying elements could improve the corrosion resistance of NdFeB magnets, but led to the decline of intrinsic magnetic properties, especially the reduction of remanence.
The reason is mainly attributed to the fact that the alloying elements are added during the ingot casting process, so that the alloying elements inevitably enter the main phase, which destroys the ordered crystal structure of the magnetic phase and reduces the intrinsic magnetic properties.

Method used

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  • Method for increasing neodymium-iron-boron permanent magnetic performance and corrosion-resisting performance

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0027] (1) NdFeB ingot alloy is made by ingot casting process, and its composition is Nd 15 Fe 余 B 6 (Dy 0.5 Al 0.4 Nb 0.2 ) (at%), the alloy is first coarsely crushed in a jaw crusher, then crushed to 80-100 mesh in a secondary crusher, and finally made into a powder with an average particle diameter of 4-5 μm by jet milling.

[0028] (2) Add boron nitride powder with a particle size of about 1 μm and dispersed treatment by ball milling and powder mixing, and its weight accounts for 0.5% of the NdFeB powder. The mixing time of the ball mill is 60 minutes, and the mixing medium is petroleum ether.

[0029] (3) The mixed powder is pressed and formed in a magnetic field orientation forming press, and the forming orientation magnetic field is 1.2T. After orientation pressing, the blank is subjected to cold isostatic pressing to increase the density of the blank, and the isostatic pressing pressure is 220 MPa.

[0030] (4) Put the blank into a high vacuum sintering furnace,...

Embodiment 2

[0036] (1) NdFeB ingot alloy is made by quick-setting sheet technology, the speed of copper roller is 2m / s, and its composition is Nd 18 Fe 余 B 5.5 Al 0.4 Dy 0.5 Ga 0.33 (at%). The alloy is first coarsely crushed in a jaw crusher, then crushed to 80-100 mesh in a secondary crusher, and finally made into a powder with an average particle diameter of 4-5 μm by jet milling.

[0037] (2) Adding dispersed magnesium oxide powder with a particle size of about 1 μm by ball milling, the weight of which accounts for 2% of the NdFeB powder. The mixing time of the ball mill is 20 minutes, and the mixing medium is petroleum ether.

[0038] (3) The mixed powder is pressed and formed in a magnetic field orientation forming press, and the forming orientation magnetic field is 1.8T. After orientation pressing, the blank is subjected to cold isostatic pressing to increase the density of the blank, and the isostatic pressing pressure is 180 MPa.

[0039] (4) Put the blank into a high vac...

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Abstract

The method includes steps: (1) using ingot-casting technique to manufacture Nd-Fe-B ingot-casting alloy, or using technique of rapid hardening sheet to produce rapid hardening sheet of Nd-Fe-B alloy; (2) first carrying out coarse crushing for alloy, then producing powder through airflow grinding; (3) adding powder of boron nitride or magnesia, and mixing them evenly; (4) pressure molding oriented mixed powders under magnetic field, and then carrying out cold isopressing process for blanks; (5) sintering and tempering blanks in high vacuum sintering furnace. Nd-Fe-B magnet produced according to the invention possesses better magnetic performance and corrosion resistance than magnetic performance and corrosion resistance of magnet without adding powder of boron nitride or magnesia.

Description

technical field [0001] The invention relates to a method in the technical field of metal materials, in particular to a method for improving the magnetic properties and corrosion resistance of NdFeB permanent magnet materials. Background technique [0002] Since its appearance in 1983, sintered NdFeB permanent magnet alloy has been widely used in microwave technology, audio-visual technology, electrical engineering, instrument technology, computer technology, automobile industry and other fields because of its excellent magnetic properties, relatively low price and sufficient resource reserves. widely used. However, the most obvious disadvantage of sintered NdFeB is its poor corrosion resistance, which greatly limits the application of this type of magnet in high temperature and humid environments, so the research on the corrosion of NdFeB is of great significance. [0003] The electrochemical corrosion of NdFeB magnets is the most serious in the environment of wet or corros...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01F1/057H01F1/08B22F3/12
Inventor 张澜庭莫文剑陈亮吴建生
Owner SHANGHAI JIAO TONG UNIV
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