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Method for obtaining high-magnetism sintered NdFeB by hot isostatic pressing low-temperature sintering

A technology of low-temperature sintering and hot isostatic pressing, which is applied in the direction of magnetic materials, magnetic objects, electrical components, etc., can solve the problems of grain growth and other problems, and achieve the effect of uniform distribution of grain boundary phases, fine grains, and large diffusion depth

Active Publication Date: 2018-07-24
UNIV OF SCI & TECH BEIJING
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] In addition, for sintered Nd-Fe-B magnets, in order to reduce the porosity of the magnet and achieve full densification of the material, it is usually necessary to increase the sintering temperature or prolong the sintering time, but this will inevitably lead to grain growth

Method used

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  • Method for obtaining high-magnetism sintered NdFeB by hot isostatic pressing low-temperature sintering
  • Method for obtaining high-magnetism sintered NdFeB by hot isostatic pressing low-temperature sintering

Examples

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Embodiment 1

[0024] 1.0cm thick NdFeB magnet with a density of 85% is covered with Pr75Cu25 ingot particles, and the particle size is 1-5mm;

[0025] Step 1: The NdFeB magnetic powder is oriented and formed under a magnetic field of 1.2T, and the blank is semi-densified and sintered in a vacuum sintering furnace at a sintering temperature of 850°C, kept for 3 hours, and the density is 85%;

[0026] Step 2: Put the semi-dense NdFeB magnet in step 1 in a glass tube, and cover its surface with Dy75Cu25 ingot particles, and then vacuum seal the glass tube with a vacuum degree of 10 -2 Above Pa;

[0027] Step 3: Put the sample of the vacuum glass sealed tube prepared in step 2 in a graphite crucible, then place it in a hot isostatic pressing machine, perform hot isostatic pressing low-temperature sintering and tempering, apply a pressure of 50 MPa, and sinter The temperature is 800°C, heat preservation for 1h, then annealing at 500°C for 2h, and slow cooling;

[0028] Step 4: The prepared NdF...

Embodiment 2

[0034] The surface of NdFeB magnet with a thickness of 1.5cm and a density of 90% is covered with Dy65Ni20Al15 ingot particles, and the particle size is 1-5mm;

[0035] Step 1: The NdFeB magnetic powder is oriented and formed under a magnetic field of 1.5T, and the blank is semi-densified and sintered in a vacuum sintering furnace. The sintering temperature is 900°C, kept for 2 hours, and the density is 90%;

[0036] Step 2: Put the semi-dense NdFeB magnet in step 1 in a glass tube, and cover the surface with Dy65Ni20Al15 ingot particles, and then vacuum seal the glass tube with a vacuum degree of 10 -2 Above Pa;

[0037] Step 3: Put the sample of the vacuum glass sealed tube prepared in step 2 in a graphite crucible, then place it in a hot isostatic pressing machine, perform hot isostatic pressing low-temperature sintering and tempering, apply a pressure of 80MPa, and sinter The temperature is 850°C, keep warm for 0.5h, then anneal at 450°C for 3h, and cool slowly;

[0038]...

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Abstract

A method for obtaining a high-magnetism sintered NdFeB by hot isostatic pressing low-temperature sintering belongs to the technical field of a rare-earth magnetic material. The method comprises the steps of performing half-density sintering on sintered NdFeB magnetic power, covering surrounding of half-density sintered NdFeB with a low-melting point diffusion alloy source, placing the NdFeB in a glass tube, performing vacuum glass tube sealing, and performing hot isostatic pressing low-temperature sintering and tempering to prepare the high-density and high-magnetism sintered NdFeB magnet. Inthe hot isostatic pressing low-temperature sintering process, the glass tube is a molten state, a layer of glass package sleeve is formed on a surface of a sample, and the sintering density of the half-density NdFeB magnet reaches 7.5g / cm<3> or above by air pressure acting on each surface of the glass package sleeve; meanwhile, the diffusion element diffusing along a boundary is accelerated underthe effect of air pressure, the depth of a diffusion layer is increased, and the thickness of the sample reaches 1.5 centimeter or above; the NdFeB magnet subjected to hot isostatic pressing low-temperature sintering has the advantages of large diffusion depth, uniform boundary phase distribution, clean boundary, fine crystal grain, high density, high 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 and low-temperature sintering. 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. With the increasing shortage of global oil resources and the severe environmental pollution caused by a large number of fuel vehicle exhaust emissions, the d...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01F1/057B22F3/15
CPCB22F3/15H01F1/0577
Inventor 杨芳邵艳茹张策芦博昕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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