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Method for obtaining high-magnetism sintered neodymium iron boron by means of hot isostatic pressure

A hot isostatic pressing and hot isostatic pressing diffusion technology, applied in the direction of magnetic materials, magnetic objects, inorganic materials, etc., can solve the problems of immature grain boundary diffusion process and limited thickness of magnet samples, and achieve good fluidity, The effect of uniform distribution of grain boundary phase and large diffusion depth

Active Publication Date: 2016-06-08
UNIV OF SCI & TECH BEIJING
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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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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  • Method for obtaining high-magnetism sintered neodymium iron boron by means of hot isostatic pressure
  • Method for obtaining high-magnetism sintered neodymium iron boron by means of hot isostatic pressure

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 a 38H commercial NdFeB magnet and process it into a sample of 30mm×30mm×8mm. Vacuum melting Dy75Cu25 alloy, cut into thin slices with a thickness of 0.5mm, the cut thin slices were polished off the scale with sandpaper, and ultrasonically cleaned in acetone;

[0024] Step 2: Place a piece of 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 the hot isostatic pressing machine, perform hot isostatic pressing diffusion heat treatment and annealing heat treatment, the applied pressure is 50MPa, the diffusion temperature is 800°C, keep it warm for 4h, and then anneal at 500°C 5h, slow cooling;

[0026] Step 4: Put the prepared NdFeB magnet into the VSM to measure the magnetic properties, ...

Embodiment 2

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

[0031] Step 1: Select N40 commercial NdFeB magnets and process them into samples of 40mm×20mm×10mm. Vacuum melting Dy65Cu20Al15 alloy, cut into thin slices with a thickness of 0.8mm, the cut thin slices were polished off the scale with sandpaper, and ultrasonically cleaned in acetone;

[0032] Step 2: Place a piece of 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 for hot isostatic pressing diffusion heat treatment and annealing heat treatment. The applied pressure is 80MPa, the diffusion temperature is 900°C, heat preservation for 5h, and then annealed at 550°C 6.5h, slow cooling;

[0034] Step 4: put the prepared NdFeB magnet into the VSM to measure the magnet...

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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 highly magnetic sintered NdFeB by hot isostatic pressing. Background technique [0002] Sintered NdFeB permanent magnet material is by far the strongest magnetic material, widely used in aerospace, automotive industry, electronic appliances, medical equipment, energy-saving motors, new energy, wind power and other fields, 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 coercive force, high energy density, high cost performance and good mechanical properties, and have played an important role in the high-tech field. [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 residual magnetism of the si...

Claims

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Application Information

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Patent Type & Authority Applications(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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