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A method for improving magnetic properties of rare earth NdFeB

A rare earth neodymium iron boron, magnetic performance technology, used in magnetic materials, magnetic objects, inductance/transformer/magnet manufacturing and other directions, can solve the problems of reduced material remanence, limited magnet thickness, etc. Effect

Active Publication Date: 2018-12-28
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

[0004] However, in process (1), element substitution will bring some adverse consequences. The magnetic moments of Nd and Fe are in the same direction, while Dy and Fe are antiferromagnetically coupled, so this element substitution will cause a significant reduction in the remanence of the material. ; In process (2), the magnet sample prepared by the grain boundary diffusion process is limited by the thickness of the magnet, and the thickness of the general sample does not exceed 8mm

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0020] (1) Throw away the RTM casting sheet of the main alloy of rare earth NdFeB and the auxiliary alloy of grain boundary with the vacuum rapid solidification furnace respectively; Wherein, the main alloy of rare earth NdFeB comprises the composition of following mass percentage: (Nd, Pr) 30.3%, Co 1%, Cu 0.2%, Al 0.5%, B0.95%, and the balance is Fe; the grain boundary auxiliary alloy RTM casting sheet includes the following components in mass percentage: Dy 60% and Fe 40%;

[0021] (2) Add 2wt% grain boundary supplementary alloy RTM casting flakes in the rare earth NdFeB main alloy, and mix evenly;

[0022] (3) Hydrogen crushing, and then through jet milling, the particle size of the obtained powder is controlled at 1.5-2 μm;

[0023] (4) Press the air-flowed powder into a square blank of 50×40×35 (mm) in an orientation magnetic field ≥ 1.4T;

[0024] (5) Put the block blank obtained in step (4) into a high vacuum sintering furnace, and sinter at 980° C. for 20 hours;

[...

Embodiment 2

[0027] (1) Throw away the RTM casting sheet with rare earth NdFeB main alloy and grain boundary auxiliary alloy respectively with vacuum quick-setting furnace; Wherein, rare earth NdFeB main alloy comprises the composition of following mass percentage: (Nd, Pr) 30.5%, Co 1.5%, Cu 0.15%, Al 0.3%, B0.95%, and the balance is Fe; the grain boundary auxiliary alloy RTM cast sheet includes the following components in mass percentage: Tb 60% and Fe 40%;

[0028] (2) Add 4wt% grain boundary supplementary alloy RTM casting flakes in the rare earth NdFeB main alloy, and mix evenly;

[0029] (3) Hydrogen crushing, and then through jet milling, the particle size of the obtained powder is controlled at 1.3-1.6 μm;

[0030] (4) Press the air-flowed powder into a square blank of 60×45×32 (mm) in an orientation magnetic field ≥ 1.4T;

[0031] (5) Put the block blank obtained in step (4) into a high vacuum sintering furnace, and sinter at 960° C. for 22 hours;

[0032] (6) High-performance r...

Embodiment 3

[0034] (1) Throw away the RTM casting sheet with rare earth NdFeB main alloy and grain boundary auxiliary alloy respectively with vacuum quick-setting furnace; Wherein, rare earth NdFeB main alloy comprises the composition of following mass percentage: (Nd, Pr) 30.5%, Co 1.2%, Cu 0.15%, Al 0.1%, B0.95%, and the balance is Fe; the grain boundary auxiliary alloy RTM cast sheet includes the following components in mass percentage: Dy 30%, Tb 30% and Fe40%;

[0035] (2) Add 0.1wt% grain boundary supplementary alloy RTM cast flakes in the rare earth NdFeB main alloy, and mix evenly;

[0036] (3) Hydrogen crushing, and then through jet milling, the particle size of the obtained powder is controlled at 1.5-1.8 μm;

[0037] (4) Press the air-flowed powder into a square blank of 72×51×30 (mm) in an orientation magnetic field ≥ 1.4T;

[0038] (5) Put the block blank obtained in step (4) into a high vacuum sintering furnace, and sinter at 950° C. for 24 hours;

[0039] (6) High-perform...

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Abstract

The invention relates to the technical field of magnetic materials, in particular to a method for improving the magnetic properties of rare earth NdFeB, comprising the following steps: mixing a grainboundary auxiliary alloy RTM casting sheet and a rare earth Nd-Fe-B main alloy, and performing hydrogen crushing, powder preparation, molding, and low-temperature long-time sintering and heat treatment to obtain a high-performance rare earth Nd-Fe-B magnet. Double alloy, grain refining and lwo-temperature long sintering are adopted, so that the influence of the remanence reduction caused by the replacement of Nd in the main phase Nd2Fe14B by the heavy rare earth in the traditional process is avoided; the heavy rare earth in the grain boundary auxiliary alloy RTM casting can be distributed uniformly in the grain boundary, so the coercivity of the magnet can be improved. The method is simple and efficient, and has no special requirements on equipment. The method is suitable for industrial production of high-performance rare earth Nd-Fe-B magnet.

Description

technical field [0001] The invention relates to the technical field of magnetic materials, in particular to a method for improving the magnetic properties of rare earth NdFeB. Background technique [0002] NdFeB has been in existence for more than 30 years. During these 30 years, the global NdFeB production has grown from less than 1 ton in 1983 to more than 100,000 tons now. It is the fastest growing magnetic material so far. The magnetic energy product (BHmax) of sintered NdFeB permanent magnets, from the original 280kJ / m 3 , increased to the current 472.8kJ / m 3 , has reached 93% of the theoretical magnetic energy product of NdFeB, and there is not much room for further improvement. Therefore, how to further improve the coercive force of the magnet is the current direction of sintering NdFeB. [0003] At present, there are two main techniques for improving the coercive force of sintered NdFeB magnets: (1) adding heavy rare earth Dy / Tb directly to the master alloy throug...

Claims

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Application Information

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IPC IPC(8): H01F1/057H01F41/02
CPCH01F1/0577H01F41/0253H01F41/0266
Inventor 黎龙贵卢慧斌胡烈平李超
Owner ZHEJIANG DONGYANG DMEGC RARE EARTH MAGNET CO LTD
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