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Sintered NdFeB rare-earth permanent magnet material with modified grain boundary phase and preparation method thereof

A rare earth permanent magnet and grain boundary phase technology, applied in the direction of magnetic materials, inorganic material magnetism, magnetic objects, etc., can solve the problem of increasing the coercive force of NdFeB permanent magnets, high addition of rare earth fluoride, remanence and magnetic energy product Reduce and other problems to achieve the effect of reducing magnetic coupling, facilitating sintering, and improving magnetic properties and resistivity

Active Publication Date: 2010-12-01
HITACHI LTD +1
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  • Application Information

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Problems solved by technology

[0005] After searching the literature of the prior art, it was found that in Japanese Patent JP2003282312A, the invention provides a R-Fe-(B, C) magnet that improves the magnetization ability of the magnet by adding cheap additives other than Dy or Tb metals and The preparation method, the addition amount of the fluoride is 3-20wt.%, but its disadvantage is that the addition amount of the rare earth fluoride is too high to cause it to agglomerate at the trifurcation grain boundary
Despite adding DyF 3 The magnet obtained a high coercive force, but its remanence and magnetic energy product decreased sharply; in the patent application CN1934283A of Japan Shin-Etsu Corporation, the invention found that adding an appropriate amount of fluorine to the NdFeB permanent magnet can form Nd-O-F compound, which can effectively inhibit the abnormal growth of the main phase grains and increase the coercive force of the NdFeB permanent magnet during the sintering process of the NdFeB permanent magnet, but its disadvantage is that it does not affect the composition of the Nd-O-F phase and Formation process conditions are fully described
Secondly, the invention does not explain and limit the shape and size of the added fluoride, because the shape and size of the additive have an important impact on the coercive force of the magnet. If the size of the added fluoride is too large, it may form a reverse Magnetized domain nucleation centers thereby reducing the coercive force of the magnet

Method used

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  • Sintered NdFeB rare-earth permanent magnet material with modified grain boundary phase and preparation method thereof
  • Sintered NdFeB rare-earth permanent magnet material with modified grain boundary phase and preparation method thereof
  • Sintered NdFeB rare-earth permanent magnet material with modified grain boundary phase and preparation method thereof

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Experimental program
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Effect test

Embodiment 1

[0045] The original materials are Nd metal, Dy metal, electrolytic pure iron, iron-boron alloy and Al, according to the pre-designed composition Nd 15 Dy 1.2 Fe 余 al 0.8 B 6 (at.%) for proportioning, using ingot casting process to make R-Fe-M-B NdFeB alloy. The alloy is first coarsely crushed in a jaw crusher, then crushed to 60-80 mesh by a secondary crusher, and then jet-milled in high-purity nitrogen to produce magnetic powder with an average particle size of 3-6 μm. 1 ~ 1000nm NdF 3 The micropowder is fully dispersed in ethanol by ultrasonic waves to form a uniform dispersion liquid with a concentration of about 1.5 mg / mL. There is no particle settlement at the bottom of the dispersion liquid. The ultrasonic time is controlled at 15-30 min. 3 In the dispersion system, ultrasonic again to make it fully mixed, the ultrasonic time is 10min. NdF 3 The amount corresponding to the addition of NdFeB magnetic powder is 0~0.5wt.%, where 0 means that no NdF is added by the sa...

Embodiment 2

[0055] The original materials are Nd-Pr alloy (80at.% is Nd), electrolytic pure iron, iron-boron alloy, according to the pre-designed composition (Nd 0.8 PR 0.2 ) 16 Fe 78 B 6 (at.%) for proportioning, using ingot casting process to make R-Fe-M-B NdFeB alloy. The technology of preparing green body is the same as embodiment 1, NdF 3 The added amount of is 0~0.8wt.%, 0 represents the reference magnet without adding fluoride by the same method. The green body is subjected to cold isostatic pressing to increase the density of the green body, and the isostatic pressure is 220MPa. Put the green body into a high-vacuum sintering furnace, sinter at 1080°C for 2 hours under vacuum, blow it with argon, and cool it at a cooling rate of about 5°C / min. After two atmosphere tempering at 900°C and 545°C, the cooling rate is 10°C / min after tempering at 900°C, and the cooling rate is about 50°C / min after tempering at 545°C, and the tempering time is 2h. The sintered NdFeB rare earth per...

Embodiment 3

[0062] The original materials are Nd-Pr alloy (80at.% is Nd), electrolytic pure iron, iron-boron alloy, according to the pre-designed composition (Nd 0.8 PR 0.2 ) 16 Fe 78 B 6 (at.%) for proportioning, using ingot casting process to make R-Fe-M-B NdFeB alloy. The technology of preparing green body is the same as embodiment 2, NdF 3 The added amount of is 0~1.5wt.%, 0 means the reference magnet without adding fluoride by the same method. The green body is subjected to cold isostatic pressing to increase the density of the green body, and the isostatic pressure is 220MPa. Put the green body into a high-vacuum sintering furnace, sinter at 1100°C for 2 hours under vacuum, and blow it with argon to cool at a cooling rate of about 10°C / min. After tempering twice at 900°C and 525°C, the tempering time is 2 hours, the cooling rate is 10°C / min after tempering at 900°C, and the cooling rate is about 50°C / min after tempering at 525°C. The sintered NdFeB rare earth permanent magnet...

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Abstract

The invention provides a sintered NdFeB rare-earth permanent magnet material with modified grain boundary phase and a preparation method thereof. The material refers to the R-Fe-M-B-based rare-earth permanent magnet of ROF compound with ordered fcc structure in the grain boundary phase, wherein R is one or more of rare earth element Nd, Pr, Dy, Tb and Y, and M is one or more of Al, Cu, Ga, Nb, Mg, Si and Mo elements. The major elements of the grain boundary phase are R, O and F elements, and the ratio of R to O and F is approximately equal to 1:1:1 (atomic percent). The preparation method is that the temperatures and cooling rates of sintering and second tempering are controlled to ensure that the F atoms in the added fluoride which can fuse with the grain boundary rich-R phase of the NdFeB magnet and the O atoms in the grain boundary phase can be in ordered arrangement to form an ordered fcc grain boundary phase. The ordered fcc grain boundary phase has better demagnetizing and coupling functions, thus facilitating to increase the coercive force of the magnet and furthest reducing the dosages of Dy and Tb.

Description

technical field [0001] The invention provides a grain boundary phase modified NdFeB rare earth permanent magnet material in the field of material technology and a preparation method thereof, specifically referring to a sintering process in which the grain boundary phase is improved by fluoride to improve its magnetic properties and resistivity NdFeB rare earth permanent magnet material and its preparation method. Background technique [0002] Rare earth permanent magnet materials are one of the basic materials to promote social progress and realize a high degree of social automation. Since the sintered NdFeB rare earth permanent magnet came out in 1983, it has rapidly become popular in many industries such as navigation and aerospace, information electronics, energy, transportation, communications, household appliances, medical equipment, etc., due to its excellent magnetic properties, relatively low price and abundant resource reserves. The field has been widely used and h...

Claims

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Application Information

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IPC IPC(8): H01F1/057H01F1/08B22F9/04B22F3/16
Inventor 小室又洋張澜庭刘琼珍单爱党沈丽萍
Owner HITACHI LTD
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