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Preparation method of NdFeB powder

A NdFeB powder technology, applied in the manufacture of inductors/transformers/magnets, magnetic objects, magnetic materials, etc., can solve the problem of increasing the number of collisions between coarse particles and fine particles, increasing the unevenness of powder particles, and accelerating airflow Slowness and other problems, to achieve the effect of uniform distribution, uniform distribution, and improved performance

Active Publication Date: 2020-03-31
廊坊京磁精密材料有限公司
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Problems solved by technology

[0002] In order to obtain high-performance sintered NdFeB magnets, it is required that the crystal grains of the magnets be as small and uniform as possible, and that the peripheries of the grains be uniformly wrapped with a layer of neodymium-rich phase as thin as possible. At present, the preparation technology of sintered NdFeB powders is mainly It is achieved by means of jet mill crushing. Since the particle size of the coarse powder after hydrogen crushing is relatively large and the distribution is very uneven, ranging from a few microns to hundreds of microns, these coarse powders enter the jet milling chamber, After the particles are accelerated to the impact area by the airflow, the number of impacts between coarse particles and fine particles is increased, which will eventually cause the inhomogeneity of the powder particles after the jet mill to be crushed, and the particle size of the coarse powder after hydrogen crushing is larger. The acceleration of the airflow is slow, and the crushing efficiency is relatively low

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  • Preparation method of NdFeB powder

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preparation example Construction

[0019] The invention provides a preparation method of NdFeB powder, comprising:

[0020] Take the coarse powder obtained by crushing the NdFeB alloy cast sheet through hydrogen absorption; the method of hydrogen absorption crushing here is a conventional method in the art;

[0021] Crush the coarse powder into an intermediate powder with an average particle size of 35-65 μm; there is no limit to what kind of pulverizer, as long as the coarse powder is crushed to 35-65 μm;

[0022] The intermediate powder is mixed with 0.03-0.1% zinc stearate by weight of the intermediate powder, and then crushed to a fine powder with an average particle size of 3-5 μm and a particle size distribution D90 / D10 of 4.2-5 with a jet mill. On the one hand, zinc stearate acts as a lubricant, on the other hand, it increases the distance between powder particles, reduces the van der Waals force between particles, prevents agglomeration, and improves the crushing efficiency of the jet mill. The obtaine...

Embodiment 1

[0029] The verification is done with 35SH sintered NdFeB materials, and 600Kg of raw materials are prepared. Among them, the iron rods must be derusted, and the rare earth materials must be oil-free, moisture-free, and rust-free. The prepared raw materials are heated and melted by intermediate frequency induction through vacuum smelting (SC) The metal is then cast onto a rotating water-cooled cooling roller through a tundish, and finally a flake-shaped fast-quenching NdFeB alloy with a columnar crystal structure is obtained, and then hydrogen-absorbing and dehydrogenating in a hydrogen-breaking furnace to crush millimeter-sized coarse particles. The coarse powder after hydrogen crushing is added to the hammer mechanical crusher, and nitrogen gas of 0.2-0.5MPa is introduced to adjust the feeding current of the crusher. The current adjustment range is 0.1-0.35A, and the feeding weight of the crusher is controlled. The weight of the material in the mill is kept at 20-60Kg, and the...

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Abstract

The invention discloses a preparation method of powder made of neodymium, iron and boron. The method includes the steps of obtaining an alloy cast sheet made of neodymium, iron and boron, and making the alloy cast sheet subjected to hydrogen absorption crushing to obtain coarse powder; crushing the coarse powder into intermediate powder with the average particle size of 35-65 microns; mixing the intermediate powder with zinc stearate the mass of which is equal to 0.03-0.1 % of the mass of the intermediate powder, then using an airflow mill to smash the mixture above into fine powder with the average particle size of 3-5 microns and the size distribution D90 / D10 of 4.2-5. Before the airflow mill is utilized for smashing, pre-smashing is conducted on the coarse powder obtained by means of hydrogen absorption crushing, the distribution uniformity of the powder made of neodymium, iron and boron is improved, and the smashing efficiency of the airflow mill is improved.

Description

technical field [0001] The invention relates to the technical field of magnetic material preparation. More specifically, the present invention relates to a preparation method of NdFeB powder. Background technique [0002] In order to obtain high-performance sintered NdFeB magnets, it is required that the crystal grains of the magnets be as small and uniform as possible, and that the peripheries of the grains be uniformly wrapped with a layer of neodymium-rich phase as thin as possible. At present, the preparation technology of sintered NdFeB powders is mainly It is achieved by means of jet mill crushing. Since the particle size of the coarse powder after hydrogen crushing is relatively large and the distribution is very uneven, ranging from a few microns to hundreds of microns, these coarse powders enter the jet milling chamber, After the particles are accelerated to the impact area by the airflow, the number of impacts between coarse particles and fine particles is increas...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01F1/057H01F41/02
CPCH01F1/0573H01F41/0253
Inventor 刘润海刘月玲
Owner 廊坊京磁精密材料有限公司
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