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Method for preparing high magnetic sintered NdFeB by hot isostatic pressing and low temperature sintering

A technology of low-temperature sintering and hot isostatic pressing, which is applied in the manufacture of magnetic materials, magnetic objects, inductors/transformers/magnets, etc., can solve the problems of narrow and small magnet sizes, achieve high coercive force, large diffusion depth, and improve diffusion The effect of uniformity

Active Publication Date: 2018-09-07
UNIV OF SCI & TECH BEIJING
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The use of grain boundary diffusion technology can save heavy rare earths Dy, Tb and other heavy rare earths to the greatest extent, and can greatly increase the coercive force of magnets without loss of remanence. However, due to the limitation of magnet surface coating thickness and diffusion depth, the magnet size is required to be narrow Small

Method used

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  • Method for preparing high magnetic sintered NdFeB by hot isostatic pressing and low temperature sintering
  • Method for preparing high magnetic sintered NdFeB by hot isostatic pressing and low temperature sintering

Examples

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Effect test

Embodiment 1

[0025] 1.5cm thick NdFeB magnet with a density of 90% is coated with Dy 2 o 3 Suspension, the coating thickness is 1.0mm;

[0026] Step 1: The NdFeB magnetic powder is oriented and formed under a magnetic field of 1.2T, and the green body is semi-densified and sintered in a vacuum sintering furnace. The sintering temperature is 950°C, kept for 1.5h, and the density is 90%;

[0027] Step 2: Put Dy 2 o 3 The powder is dispersed in anhydrous ethanol, and after mixing evenly, a suspension is obtained with a viscosity of 200mpa.s; the suspension is evenly coated on the surface of a sintered NdFeB magnet with a density of 90% in a glove box, and the coating thickness is 1.0mm, vacuum-dried in a vacuum oven at a drying temperature of 40°C for 45 minutes;

[0028] Step 3: Containing Dy 2 o 3 The coated semi-dense sintered NdFeB is placed in a glass tube, and then the glass tube is vacuum sealed with a vacuum degree of 10 -2 Above Pa;

[0029] Step 4: Put the sample of the vacu...

Embodiment 2

[0035] 1.5cm thick NdFeB magnet with 87% density coated with Tb 2 o 3 Suspension, the coating thickness is 0.8mm;

[0036] Step 1: The NdFeB magnetic powder is oriented and formed under a magnetic field of 1.8T, and the green body is semi-densified and sintered in a vacuum sintering furnace. The sintering temperature is 900 ° C, kept for 1 hour, and the density is 87%;

[0037] Step 2: Put Tb 2 o 3 Disperse the powder in acetone and mix it uniformly to obtain a suspension with a viscosity of 300mpa.s; in a glove box, evenly coat the suspension on the surface of a sintered NdFeB magnet with a density of 87%, and the coating thickness is 0.8 mm, vacuum-dried in a vacuum drying oven at a drying temperature of 35°C for 35 minutes;

[0038] Step 3: Containing Tb 2 o3 The coated semi-dense sintered NdFeB is placed in a glass tube, and then the glass tube is vacuum sealed with a vacuum degree of 10 -2 Above Pa;

[0039] Step 4: Put the sample of the vacuum glass sealed tube in...

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Abstract

The invention relates to a method for preparing high magnetic sintered NdFeB by hot isostatic pressing and low temperature sintering and belongs to the technical field of rare earth magnetic materials, wherein sintered NdFeB magnetic powder is subject to semi-densified sintering, wherein the density is of 85% to 95%; then, a turbid liquid containing a heavy rare earth compound and having a viscosity of 100 to 500 mpa.s is coated on the periphery of the semi-densified sintered NdFeB; vacuum glass tube sealing is carried out, low temperature sintering is carried out at 700-900 DEG C through hotisostatic pressing, and tempering is carried out at 400-500 DEG C so as to prepare the high-density and high-magnetic sintered NdFeB magnet. Coatings of Dy2S3, Dy2O3, Tb2O3, DyF3 or DyH3 have good adhesion to the semi-densified sintered NdFeB magnet. During the hot isostatic pressing and low temperature sintering process, the heavy rare earth elements diffuse along the grain boundary and pores. Under the gas pressure in all directions, the diffusion rate is faster, thereby effectively increasing the diffusion depth and diffusion uniformity as well as effectively increasing the sintering density of the magnet and refining the grain size.

Description

technical field [0001] The invention belongs to the technical field of rare earth magnetic materials, and provides a method for preparing high-magnetic sintered NdFeB by hot isostatic pressing and low-temperature sintering. Background technique [0002] Sintered NdFeB permanent magnet material is the third generation permanent magnet, which was invented by Japanese scholars in 1983. Because of its extremely high coercive force and magnetic energy product, it is called "Magnetic King". Widely used in aerospace, automobile industry, electronic appliances, medical equipment, energy-saving motors, new energy, wind power and other fields, it is the fastest growing permanent magnet material with the best market prospects in the world today. NdFeB materials have outstanding advantages such as high magnetic energy product, high coercive force, high energy density, high cost performance and good mechanical properties, and have played an important role in the high-tech field. With t...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01F41/02H01F1/057B22F3/10B22F3/15B22F3/24
CPCB22F3/1007B22F3/15B22F3/24B22F2003/242B22F2003/248B22F2999/00H01F1/0577H01F41/0253H01F41/0266H01F41/0293B22F2202/05
Inventor 杨芳张策芦博昕邵艳茹郭志猛隋延力陈存广冯钊红陆天行李沛
Owner UNIV OF SCI & TECH BEIJING
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