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A method for improving the magnetic properties of sintered NdFeB by grain boundary diffusion

A technology of grain boundary diffusion and NdFeB, which is applied in the direction of magnetic materials, magnetic objects, and inorganic materials, can solve the problems of magnet sample thickness limitation and immature grain boundary diffusion process, and improve the coercive force and distribution of magnets. High uniformity and thickness consistency, the effect of improving depth

Active Publication Date: 2017-08-11
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 improving the magnetic properties of sintered NdFeB by grain boundary diffusion
  • A method for improving the magnetic properties of sintered NdFeB by grain boundary diffusion

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0025] 1.0cm thick NdFeB magnet with a density of 92% is coated with Dy 2 o 3 Suspension, the coating thickness is 0.5mm;

[0026] Step 1: Orient the sintered NdFeB magnetic powder under a magnetic field of 1.5T, and make a green body under 200MPa cold isostatic pressing;

[0027] Step 2: Carry out semi-densification sintering of the blank in a vacuum sintering furnace, the sintering temperature is 940°C, heat preservation for 2 hours, and the density is 92%;

[0028] Step 3: Put Dy 2 o 3 The powder is dispersed in anhydrous ethanol, and after mixing evenly, a suspension is obtained with a viscosity of 100mpa.s;

[0029] Step 4: Evenly coat the suspension on the surface of a sintered NdFeB magnet with a density of 92%, with a coating thickness of 0.5mm, and dry it in a vacuum drying oven at a drying temperature of 80°C for 1 hour;

[0030] Step 5: Incorporate Dy 2 o 3 The coated semi-dense sintered NdFeB is vacuum sintered and tempered in a vacuum sintering furnace. Th...

Embodiment 2

[0037] 1.0cm thick NdFeB magnet with 95% density coated with Tb 2 o 3 Suspension, the coating thickness is 1mm;

[0038] Step 1: Orientate the sintered NdFeB magnetic powder under a magnetic field of 2.0T, and make a green body under cold isostatic pressing of 200MPa;

[0039] Step 2: Carry out semi-densification sintering of the blank in a vacuum sintering furnace, the sintering temperature is 950°C, the temperature is kept for 3 hours, and the density is 95%;

[0040] Step 3: Put Tb 2 o 3 The powder is dispersed in a mixed solvent of propylene glycol and polyvinyl alcohol, and after mixing evenly, a suspension is obtained with a viscosity of 200mpa.s;

[0041] Step 4: Evenly coat the suspension on the surface of a sintered NdFeB magnet with a density of 95%, with a coating thickness of 1mm, and dry it in a vacuum drying oven at a drying temperature of 50°C for 2 hours;

[0042] Step 5: Incorporate Tb-containing 2 o 3 The coated semi-dense sintered NdFeB is vacuum sint...

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Abstract

The invention discloses a method for improving the magnetic performance of sintered NdFeB through grain boundary diffusion, and belongs to the technical field of rare earth magnetic materials. The method comprises the steps that sintered NdFeB magnetic powder is subjected to semi-densification sintering, wherein the density is 90-95%; the periphery of the semi-densification sintered NdFeB is coated with turbid liquid, with the viscosity of 100-500 mpa.s, containing heavy rare earth compounds, the vacuum drying is carried out, coatings with heavy rare earth elements areobtained on the surface of a semi-densification sintered NdFeB magnet, then sintering at 1040-1080 DEG C is carried out for 2-3 h, primary tempering at 900-940 DEG C is carried out for 1-3 h, secondary tempering at 480-550 DEG C is carried out for 2-4 h, and the high-magnetism sintered NdFeB material is obtained. Certain adhesive force is formed between the semi-densification sintered NdFeB magnet and the coatings such as Dy2O3, Tb2O3, DyF3 and DyH3, the heavy rare earth elements enter the NdFeB magnet in the sintering process, the organizational structure and components at the combined position of a grain boundary and a main phase are improved, the heavy rare earth elements can be more easily diffused into the NdFeB magnet, the distribution uniformity and thickness consistency are high, and the depth of the diffusion layer is greatly increased.

Description

technical field [0001] The invention belongs to the technical field of rare earth magnetic materials and provides a method for improving the magnetic properties of sintered NdFeB by grain boundary diffusion. 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". NdFeB rare earth permanent magnet materials currently occupy more than 60% of the permanent magnet material market share. With the development of new energy systems such as hybrid electric vehicles (HEV), pure electric vehicles (EV) and wind power generation, in permanent magnet materials The sintered NdFeB permanent magnet material with the highest magnetic energy product is the key to realize the miniaturization, light weight and high power of the motor. [0003] After more than 20 years of research and de...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01F1/057H01F1/08B22F3/16
CPCB22F3/16H01F1/0571H01F1/0575
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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