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A method for obtaining high magnetic sintered NdFeB by hot isostatic pressing

A technology of hot isostatic pressing and hot isostatic pressing diffusion, which is applied in the direction of magnetic materials, magnetic objects, inorganic materials, etc., can solve the problems of magnet sample thickness limitation and immature grain boundary diffusion process, etc. Uniform grain boundary phase distribution and low melting point

Active Publication Date: 2017-12-22
UNIV OF SCI & TECH BEIJING
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, due to the immaturity of the grain boundary diffusion process, the sample thickness of the magnet produced by the grain boundary diffusion method is greatly limited, and the general sample thickness does not exceed 5mm

Method used

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  • A method for obtaining high magnetic sintered NdFeB by hot isostatic pressing
  • A method for obtaining high magnetic sintered NdFeB by hot isostatic pressing

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0022] The upper and lower surfaces of 8mm thick 38H NdFeB magnets are covered with 0.5mm thick Dy75Cu25 alloy sheets;

[0023] Step 1: Select 38H commercial NdFeB magnets and process them into 30mm×30mm×8mm samples. The Dy75Cu25 alloy was smelted in vacuum, and cut into thin slices with a thickness of 0.5 mm. The cut thin slices were polished with sandpaper to remove the oxide skin, and placed in acetone to ultrasonically clean;

[0024] Step 2: Place a Dy75Cu25 alloy sheet on the upper and lower surfaces of the NdFeB magnet, and place the alloy sheet and the magnet in a graphite crucible;

[0025] Step 3: Put the graphite crucible prepared in step 2 in a hot isostatic pressing machine, and perform hot isostatic pressing diffusion heat treatment and annealing heat treatment. 5h, slow cooling;

[0026] Step 4: Put the prepared NdFeB magnet into the VSM to measure the magnetic properties. The results are shown in Table 1. It can be seen that the Dy / Cu diffusion effect of the...

Embodiment 2

[0030] The upper and lower surfaces of the 1cm thick N40 NdFeB magnet are covered with 0.8mm thick Dy65Cu20Al15 alloy sheets;

[0031] Step 1: Select N40 commercial NdFeB magnets and process them into 40mm×20mm×10mm samples. The Dy65Cu20Al15 alloy was smelted in vacuum, and cut into thin slices with a thickness of 0.8 mm. The cut thin slices were polished with sandpaper to remove the oxide scale, and placed in acetone to ultrasonically clean;

[0032] Step 2: Place a Dy65Cu20Al15 alloy sheet on the upper and lower surfaces of the NdFeB magnet, and place the alloy sheet and the magnet in a graphite crucible;

[0033] Step 3: Put the graphite crucible prepared in step 2 in a hot isostatic pressing machine, and perform hot isostatic pressing diffusion heat treatment and annealing heat treatment. The applied pressure is 80 MPa, the diffusion temperature is 900 ° C, the temperature is kept for 5 hours, and then annealed at 550 ° C. 6.5h, slow cooling;

[0034] Step 4: Put the pre...

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Abstract

The invention provides a method for obtaining high-magnetism sintered neodymium iron boron by means of hot isostatic pressure and belongs to the technical field of rare earth magnetic materials. According to the method, a sintered neodymium iron boron body and a low-melting-point diffusion alloy piece are stacked together, pressure is exerted in a hot isostatic pressure machine and kept for carrying out diffusing heat treatment and annealing heat treatment, diffusing heat treatment temperature ranges from 700 DEG C to 900 DEG C, the temperature is preserved for 3-5 h, annealing heat treatment is carried out for 2-10 h at the temperature of 400 DEG C-600 DEG C, and slow cooling is carried out to obtain the sintered neodymium iron boron body diffused uniformly. In the hot isostatic pressure diffusing heat treatment process, the low-melting-point diffusion alloy piece is melted to liquid to wrap the surface of neodymium iron boron, diffusion kinetic energy of the melted diffusion alloy is increased due to pressure, diffusion of elements such as Dy, Cu, Al and Ni in a crystal boundary can be accelerated, and the depth of a diffusion layer is increased. A diffusion source is melted into liquid, and the processes of fine powder manufacturing and surface coating can be omitted. The neodymium iron boron body after the hot isostatic pressure is diffused has the advantages of being large in diffusion depth, uniform in crystal boundary phase distribution, clear in boundary, high in coercivity and the like.

Description

technical field [0001] The invention belongs to the technical field of rare earth magnetic materials, and provides a method for obtaining high magnetic sintered NdFeB by hot isostatic pressing. Background technique [0002] Sintered NdFeB permanent magnet material is by far the strongest magnetic material. It is 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 in the world today. , The permanent magnet material with the best market prospect. NdFeB materials have outstanding advantages such as high magnetic energy product, high coercivity, high energy density, high cost performance and good mechanical properties, and have played an important role in the field of high-tech. [0003] After more than 20 years of research and development, a reasonable alloy composition and a mature preparation process have been designed to make the remanence B of the s...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01F1/057H01F1/08B22F3/15B22F3/24
CPCB22F3/15B22F3/24B22F2003/248H01F1/0575
Inventor 郭志猛杨芳隋延力石韬杨薇薇陈存广罗骥郝俊杰
Owner UNIV OF SCI & TECH BEIJING
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