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Preparation method of Nd-Fe-B magnet

A technology of neodymium iron boron and magnets, which is applied in the direction of magnetic objects, inductance/transformer/magnet manufacturing, magnetic materials, etc., can solve the problems of reduced coercive force Hcj, increased difficulty of the preparation process, and reduced residual magnetism Br, etc., to achieve improved Effects of processing performance, impact reduction, and stable performance

Inactive Publication Date: 2016-08-10
NINGBO HONGLEI MAGNETICS
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

At a temperature of 295K, the saturation magnetic polarization of Ce2Fe14B Js=1.17T, anisotropy field HA=2069.6kA / m, while the saturation magnetic polarization of Nd2Fe14B Js=1.60T, anisotropy field HA=5810.0kA / m , so when cerium Ce is used instead of neodymium Nd, the magnetic properties will be reduced, and the residual magnetism Br will be slightly reduced, but the coercive force Hcj will be greatly reduced, so the general coercive force of cerium-containing sintered NdFeB It will be relatively low. In most cases, the magnets containing cerium are N materials with low coercive force (Hcj≥960kA / m)
At the same time, due to the easy oxidation of cerium, it will also increase the difficulty of the preparation process.

Method used

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  • Preparation method of Nd-Fe-B magnet
  • Preparation method of Nd-Fe-B magnet
  • Preparation method of Nd-Fe-B magnet

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0028]In this embodiment, the alloy composition is (PrNd)27.2Gd4.0Al0.8Cu0.2Co1.0B0.98Febal (content is weight percent, wt%), which is smelted in a vacuum induction casting furnace to prepare an alloy cast sheet of this composition. Then the alloy cast flakes are crushed into a coarse powder with an average particle size of 50 μm by hydrogen crushing, and then ultrafinely pulverized by a high-pressure water jet to grind the coarse powder into a fine powder with an average particle size of 3.3 μm. The micropowder is divided into two groups: the first group is the micropowder without adding titanium powder, which is mixed by a three-dimensional mixer, and the mixing time is 6 hours, and then sifted with a 200-mesh sifter; the second group is Add the micropowder of titanium powder, add the titanium powder that weight percent is 0.2wt% in micropowder, the average particle size of titanium powder is 15 μ m, carry out mixing by three-dimensional mixing machine, mixing time is 6 hours...

Embodiment 2

[0038] In this embodiment, the alloy composition is (PrNd)27.2Gd4.0Al0.8Cu0.2Co1.0B0.98Febal (content is weight percent, wt%), which is smelted in a vacuum induction casting furnace to prepare an alloy cast sheet of this composition. Then the alloy cast flakes are crushed into a coarse powder with an average particle size of 100 μm by hydrogen breaking, and then ultrafinely pulverized by a high-pressure water jet to grind the coarse powder into a fine powder with an average particle size of 2.7 μm. Add the titanium powder that weight percent is 0.2wt% to micropowder, the average particle size of titanium powder is 8 μ m, carry out mixing by three-dimensional mixing machine, mixing time is 6 hours, then use mesh number to be 200 mesh powder sieving machines to sieve powder . The micropowder is respectively pressed and formed in a closed press under the protection of nitrogen. The size of the green compact is a square of 57.5×30×48, and the oxygen content in the closed press is ...

Embodiment 3

[0040] In this embodiment, the alloy composition is (PrNd)27.2Gd4.0Al0.8Cu0.2Co1.0B0.98Febal (content is weight percent, wt%), which is smelted in a vacuum induction casting furnace to prepare an alloy cast sheet of this composition. Then the alloy cast flakes are crushed into a coarse powder with an average particle size of 200 μm by hydrogen crushing, and then ultrafinely pulverized by a high-pressure water jet to grind the coarse powder into a fine powder with an average particle size of 3.8 μm. Add titanium powder with a weight percentage of 0.2wt% in the micropowder, the average particle size of the titanium powder is 47 μm, mix the mixture through a three-dimensional mixer, the mixing time is 6 hours, and then sieve the powder with a 200-mesh sifter . The micropowder is respectively pressed and formed in a closed press under nitrogen protection. The size of the compact is 57.5×30×48 squares, and the oxygen content in the closed press is required to be lower than 970ppm. ...

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Abstract

The invention discloses a preparation method of a Nd-Fe-B magnet. The preparation method comprises the following steps of (a) preparing magnet alloy from alloy A and alloy B to obtain a casting sheet; (b) smashing and milling the casting sheet to obtain alloy micro powder, wherein the smashing and milling comprises two steps of rough powder preparation and micro powder preparation which are carried out successively; (c) pressing and forming the alloy micro powder, wherein the alloy micro powder is pressed and formed in an environment where the oxide content is less than 1,000ppm to obtain a blank; and (d) sintering the blank, wherein the blank is subjected to sintering and aging, wherein the constituent of the magnet alloy is R<x>M<y>B<z>Fe<residual>, and in micro powder preparation, the alloy micro powder is obtained by high-pressure water jet ultrafine smashing. According to the scheme, two constituent materials are mixed, cerium is mainly distributed in a centralized manner in a main phase of a crystal grain and is less distributed at the boundary of the crystal gain, the reduction of coercivity of cerium is greatly reduced by improving such a microstructure, so that and the magnet with higher coercivity and low cost can be fabricated.

Description

technical field [0001] The invention relates to a method for preparing a permanent magnet, in particular to a method for preparing an NdFeB magnet. Background technique [0002] NdFeB magnets are mainly intermetallic compounds composed of rare earth elements R, iron and boron. R is mainly neodymium or a combination of neodymium and other rare earth elements, and sometimes cobalt, aluminum, vanadium and other elements are used to replace part of iron. It is mainly divided into sintered NdFeB and bonded NdFeB. Bonded NdFeB is magnetic in all directions and is corrosion-resistant; and sintered NdFeB is easy to corrode, and the surface needs to be coated. Generally, there are galvanized, nickel, Environmental protection zinc, environmental protection nickel, nickel copper nickel, environmental protection nickel copper nickel, etc. Sintered NdFeB is generally divided into axial magnetization and radial magnetization, depending on the required working surface. [0003] NdFeB pe...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01F41/02H01F1/057
CPCH01F41/0266H01F1/0576H01F1/0577H01F41/0293
Inventor 张宏芳
Owner NINGBO HONGLEI MAGNETICS
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