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Method for preparing permanent magnetism block body of Nano crystal neodymium, boron

A technology of NdFeB and permanent magnet block, which is applied in the direction of magnetic objects, inductor/transformer/magnet manufacturing, magnetic materials, etc., and can solve problems such as low efficiency, long heating time, uneven grain growth, etc.

Active Publication Date: 2010-09-15
SICHUAN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The current of direct heating is generally small, the heating rate is generally less than 50K / s, the heating time is longer, and the grains are easy to coarsen; monomer production, low efficiency; mold life is short, power and die consumption are high, product cost High; in the preparation process of MQII magnets, the rare earth content generally exceeds 13%, and the quenched powder structure is dominated by Nd 2 Fe 14 B is the main phase, and the Nd-rich phase is surrounded by the main phase Nd 2 Fe 14 On the grain boundary of B, at a certain temperature, the Nd-rich phase with a low melting point will melt, making Nd 2 Fe 14 B is immersed in the Nd-rich liquid phase, so the sintering process is liquid phase sintering, which can easily cause grain growth. At the same time, under a certain pressure, Nd parallel to the direction of pressure 2 Fe 14 B grains grow due to high strain energy, resulting in uneven grain growth

Method used

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  • Method for preparing permanent magnetism block body of Nano crystal neodymium, boron
  • Method for preparing permanent magnetism block body of Nano crystal neodymium, boron
  • Method for preparing permanent magnetism block body of Nano crystal neodymium, boron

Examples

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Effect test

Embodiment 1

[0013] In this example, the amorphous Nd 11.5 Dy 0.5 Fe 75.9 Nb 1 co 0.5 B 6.1 The magnetic powder is pressed into a preform on a press in advance, and the density of the preform is 6.2g / cm 3 , The molded bodies are all cylindrical samples of φ10mm. It is loaded between the two punches of the electric field activated pressure-assisted sintering equipment and clamped, and the pressureless sintering is carried out under the condition of high vacuum in the working room. The sintering temperature is 700°C, the heating rate is 2000°C / s, and the holding time is 5 minutes. After the sintering is completed, cool to room temperature and take out the magnet. The magnetic properties of the sintered nanocrystalline NdFeB magnet are remanence Br=0.67T, magnetic induction coercive force H cb =376kA / m, intrinsic coercive force H cj =700kA / m, maximum energy product (BH) m =68kJ / m 3 .

Embodiment 2

[0015] In this example, using amorphous Nd 11 Fe 73 co 7 Zr 3 B 6 Magnetic powder, pressed on a press to form a green body, the density of the green body is 5.4g / em 3 , The molded bodies are all cylindrical samples of φ10mm. After the initial NdFeB blank is loaded, the working room is evacuated to a high vacuum, and a pressure of 50MPa is applied, and then sintered in the electric field activation pressure-assisted sintering equipment. The sintering temperature is 550°C, the heating rate is 1000°C / s, and the holding time is 20 minutes. After the sintering is completed, cool to room temperature and take out the magnet. The density of the sintered nanocrystalline NdFeB magnet is 7.4g / cm 3 , the magnetic properties are remanence Br=0.74T, magnetic induction coercive force H cb =410kA / m, intrinsic coercive force H cj =840kA / m, maximum energy product (BH) m =95kJ / m 3 .

Embodiment 3

[0017] In this example, using amorphous Nd 11 Fe 74 co 6 Zr 3 B 6 Magnetic powder, pressed into a blank on a press, the density of the blank is 6.19g / cm 3 , The molded bodies are all cylindrical samples of φ10mm. Put the blank into the electric field activation pressure-assisted sintering equipment, and backfill Ar after the studio is evacuated 2 Gas to 0.1MPa for sintering. A pressure of 100MPa is applied during the sintering process, the sintering temperature is 490°C, the heating rate is 1500°C / s, and the holding time is 35 minutes. After the sintering is completed, cool to room temperature and take out the magnet. The density of the sintered nanocrystalline NdFeB magnet is 6.6g / cm 3 , the magnetic properties are remanence Br=0.62T, magnetic induction coercive force H cb =332kA / m, intrinsic coercive force H cj =627kA / m, maximum energy product (BH) m =54kJ / m 3 .

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Abstract

The method for preparing material of permanent magnetism block body in Nano crystal Nd-Fe-B includes steps: first, direct pressing any one of non-crystalline Nd-Fe-B powder without any additive into semi finished product; loading and clamping semi finished product to two press heads of electric field activated pressure assistant sintering equipment; under high vacuum, or after backfilling N2 or inert protection gases, in conditions of 0-110Mpa pressure, heating rate 0-2000 deg.C / s, temperature range 400-850 deg.C, and holding time 1-45 minutes, implementing crystallization and agglomeration of block body in non-crystalline Nd-Fe-B; cooling to room temperature to obtain permanent magnetism block body in Nano crystal Nd-Fe-B. The invention possesses features of instant heating up, large current and short time agglomeration to realize integration of crystallization and agglomeration. Thus, the method restrains growing up crystal grain, not destroying microscopic structure and performance.

Description

technical field [0001] The invention relates to a method for preparing a nanocrystalline NdFeB permanent magnet block material, which belongs to the field of magnetic materials. Background technique [0002] In 1983, Japan's Sumitomo Metal Corporation invented NdFeB permanent magnets for the first time. Because of its high remanence, high coercive force, high magnetic energy product and good dynamic recovery characteristics, it quickly set off a wave of development worldwide. Research boom. At present, nanocrystalline rare earth permanent magnet materials and devices are one of the key research and development rare earth functional material technologies at home and abroad. Nanocrystalline quick-quenched NdFeB magnetic powder and bonded NdFeB magnets are the first nanocrystalline rare earth permanent magnet materials and device technologies to be applied in practice. . Because of its good consistency of magnetic properties, easy molding, high precision, and high material ut...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01F41/02H01F1/08H01F1/057H01F7/02B22F3/00
Inventor 刘颖张龙凤叶金文张然李梦李开华
Owner SICHUAN UNIV