Preparation method of laser pulse perforation assisted diffusion high-coercivity neodymium iron boron

A laser pulse, high coercivity technology, used in the manufacture of inductors/transformers/magnets, magnetic objects, magnetic materials, etc., can solve the problems of broken magnet structure, reduction of magnet coercivity, uneven distribution of heavy rare earth elements, etc. , to achieve the effect of improving uniformity, increasing coercivity, and increasing specific surface area

Active Publication Date: 2021-02-19
CHINA JILIANG UNIV
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  • Abstract
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  • Application Information

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Problems solved by technology

However, the traditional grain boundary diffusion technology is all coating on the surface of the magnet. Due to the limited diffusion depth of heavy rare earth elements, the distribution of heavy rare earth elements in the magnet is extremely uneven, and the coercivity enhancement is limited. It is necessary to increase the heat treatment temperature and Over time, excessive heavy rare earth elements will enter the magnet coating side, thereby breaking the magnet structure and reducing the coercive force of the magnet

Method used

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  • Preparation method of laser pulse perforation assisted diffusion high-coercivity neodymium iron boron
  • Preparation method of laser pulse perforation assisted diffusion high-coercivity neodymium iron boron

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Embodiment 1

[0020] Embodiment 1: A preparation method of laser pulse perforation assisted diffusion high coercive force NdFeB, comprising the following steps:

[0021] Step (1) Preparation of diffusion source:

[0022] The heavy rare earth metal Tb and the low melting point metal Al are smelted at an atomic ratio of 0.3:1 to form a master alloy, and the master alloy is high-energy ball milled for 12 hours to form a nanometer to micron powder, and the powder is mixed with an acetone solution to form a mixed solution of a diffusion source;

[0023] Step (2) NdFeB laser perforation:

[0024] Using femtosecond to nanometer laser pulses, the laser wavelength is 800nm, the pulse duration is 300fs, the pulse intensity is 150uJ, the spot size is 10μm, and the surface of the NdFeB magnet with a size of 10mm×10mm×10mm is perforated. The shape of the hole is as follows figure 1 As shown, the distance between the holes is 0.5mm, and a coal ball-shaped magnet is formed;

[0025] Step (3) NdFeB surfa...

Embodiment 2

[0032] Step (1) Preparation of diffusion source:

[0033] The heavy rare earth metal Dy and the low melting point metal Al are smelted at an atomic ratio of 0.5:1 to form a master alloy, and the master alloy is high-energy ball milled for 24 hours to form a nanometer to micrometer powder, and the powder is mixed with an acetone solution to form a mixed solution of a diffusion source;

[0034] Step (2) NdFeB laser perforation:

[0035] Using femtosecond to nanometer laser pulses, the laser wavelength is 800nm, the pulse duration is 1ns, the pulse intensity is 100uJ, the spot size is 25μm, and the surface of the NdFeB magnet with a size of 20mm×20mm×20mm is perforated, and the distance between the holes is 1mm, forming a briquette magnet;

[0036] Steps (3 NdFeB surface and internal coating:

[0037] Immerse the briquette-shaped magnet in the mixed solution of the diffusion source, take it out, and pre-fire it at 100°C for 4 hours under the protection of nitrogen to obtain a m...

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Abstract

The invention discloses a preparation method of laser pulse perforation assisted diffusion high-coercivity neodymium iron boron, which comprises the following steps: smelting Dy and other heavy rare earth metals and Al and other low-melting-point metals according to an atomic ratio to form a mother alloy, carrying out high-energy ball milling on the mother alloy to form nano-scale to micron-scalepowder, and mixing the powder with an organic solvent to form a diffusion source mixed solution; perforating the surface of the neodymium-iron-boron magnet by using femtosecond to nano laser pulses toform a coal ball-shaped magnet; immersing the coal ball-shaped magnet into the diffusion source mixed solution, taking out the magnet, and presintering at low temperature under the protection of nitrogen to obtain a magnet with a diffusion source coating inside and on the surface of the magnet; and finally, carrying out heat treatment on the magnet under argon protection and a strong magnetic field to obtain the neodymium-iron-boron magnet with high coercive force. According to the method, the specific surface area of the coating layer and the magnet is increased, the heavy rare earth elements are subjected to three-dimensional diffusion in the magnet, the distribution uniformity of the heavy rare earth elements in the magnet is effectively improved, the coercive force of the neodymium-iron-boron permanent magnet is improved, and the method is simple in process, easy to operate and suitable for batch production.

Description

technical field [0001] The invention relates to the technical field of magnetic materials, in particular to a method for preparing a high-coercivity sintered NdFeB magnet. Background technique [0002] The mechanism of coercive force enhancement has always been one of the key scientific issues of permanent magnetic materials, which is complex and interesting. The coercive force of ternary sintered NdFeB deteriorates significantly with the increase of temperature. In order to meet the needs of high temperature use, it is necessary to enhance its coercive force at room temperature. The coercive force of an actual magnet is obtained by transforming the magnetocrystalline anisotropy field through a certain microstructure. The traditional preparation method needs elements such as heavy rare earth Dy / Tb to replace Nd to improve the main phase to achieve the enhancement of coercive force. However, the use of heavy rare earths Dy / Tb leads to a substantial increase in material cost...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01F41/02H01F1/057
CPCH01F41/0253H01F41/0293H01F1/057
Inventor 杨杭福黄霞妮吴琼泮敏翔余能君华思昊葛洪良
Owner CHINA JILIANG UNIV
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