Method for preparing high-coercivity sintered Nd-Fe-B permanent magnet

A high coercivity, NdFeB technology, used in the manufacture of magnetic objects, magnetic materials, inductors/transformers/magnets, etc., can solve problems such as low production efficiency, large amount of precious metal Dy, and reduced magnetization

Active Publication Date: 2014-06-04
EARTH PANDA ADVANCE MAGNETIC MATERIAL
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The different ways of adding Dy have a great influence on the performance. One is direct alloying, that is, metal Dy is added when the master alloy is smelted. However, Dy 2 Fe 14 The saturation magnetization of B is only about 0.7T, less than Nd 2 Fe 14 Half of B's ​​1.60T, so adding Dy to increase the coercive force will lead to a decrease in magnetization
The second addition method - double alloy method, that is,

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0026] Raw materials are made of various pure metals Nd, Pr, Dy, Al, Ga, Co, Fe and alloys B-Fe, Nb-Fe, etc. according to the formula requirements of the brand N45, and then melted into cast pieces in a vacuum induction casting furnace. The sintered Nd-Fe-B magnetic material blank was prepared by hydrogen crushing-jet milling-powder mixing-orientation pressing-isostatic pressing-sintering process. Test the magnetic properties of the sintered NdFeB magnetic material blank at this time. The above-mentioned sintered NdFeB magnetic material is chamfered for 8 hours. Put the chamfered NdFeB magnetic material in ethanol for preliminary degreasing. The magnetic material is soaked and cleaned in the cleaning solution for 5 minutes, and then the process of water washing and secondary water washing is carried out. Place the cleaned NdFeB magnetic material in a citric acid solution with a mass concentration of 10% to activate the surface of the NdFeB magnetic material for 10 seconds, a...

Embodiment 2

[0031] Raw materials are made of various pure metals Nd, Pr, Dy, Al, Ga, Co, Fe and alloys B-Fe, Nb-Fe, etc. according to the enterprise brand 42M formula requirements, and then melted into cast pieces in a vacuum induction casting furnace , the sintered Nd-Fe-B magnetic material blank was obtained by hydrogen crushing-jet milling-powder mixing-orientation pressing-isostatic pressing-sintering process. Test the magnetic properties of the sintered NdFeB magnetic material blank at this time. The above-mentioned sintered NdFeB magnetic material is chamfered for 6 hours. Put the chamfered NdFeB magnetic material in an alcohol solvent for preliminary degreasing, wash it with water after the preliminary degreasing, and place it in an acid solution for secondary degreasing and surface deoxidation treatment. After the deoxidation treatment, the NdFeB The boron magnetic material is soaked and cleaned in the cleaning solution for 7 minutes, and then the process of water washing and sec...

Embodiment 3

[0036] Raw materials are made of various pure metals Nd, Pr, Dy, Al, Ga, Co, Fe and alloys B-Fe, Nb-Fe, etc. according to the enterprise brand 42M formula requirements. The preparation process of the sintered NdFeB blank and the pretreatment process for electroplating are the same as in Examples 1 and 2, and the parameters in the process are changed as follows:

[0037] (1) The chamfering time is 8 hours

[0038] (2) The molar ratio of heavy rare earth elements to the metal element nickel in the nickel plating layer is 10%

[0039] (3) Place the dried sintered NdFeB magnetic material in a vacuum heat treatment furnace, firstly heat-treat at 650°C for 3 hours, and then heat-treat at 350°C for 3 hours.

[0040] It was tested for magnetic properties. The magnetic properties of the sintered NdFeB magnetic material blank and the magnetic properties of the magnet after high-temperature heat treatment after electroplating composite coating are listed in Table 3.

[0041] table 3 ...

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Abstract

The invention discloses a method for preparing a high-coercivity sintered Nd-Fe-B permanent magnet. The method includes the following steps that firstly, the vacuum rapid hardening technology is used for preparing Nd-Fe-B alloy magnetic material blank; secondly, chamfering, cleaning, washing, surface modifying and washing are sequentially performed on the blank; thirdly, a processed permanent magnet is placed to a nickel/heavy rare earth composite coating for being electroplated; fourthly, a sintered Nd-Fe-B magnetic material is placed into a vacuum heat treatment furnace to receive heat treatment. With the technology of compositing heavy rare earth on a nickel-plate, heavy rare earth solid matter can be effectively utilized, and maximum benefits of rare earth resources are achieved. Meanwhile, it is ensured that the proportion of the content of the heavy rare earth in the nickel-plate is stable, volatile matter which is prone to decomposition does not exist in the nickel-plate in subsequent heat treatment to pollute a vacuum heat treatment system, a production device with infiltration of the heavy rare earth can be stable continuously, the application range of a technology is wider, and the method can be popularized and applied in an enterprise more easily.

Description

technical field [0001] The invention relates to the field of magnetic materials, in particular to a method for preparing a sintered NdFeB permanent magnet with high coercive force. Background technique [0002] With the rise of the hybrid electric vehicle (HEV) industry, sintered NdFeB magnets for automobiles require magnets with high coercive force and high temperature resistance. The anisotropy field of sintered Nd-Fe-B compound, that is, the theoretical limit value of coercive force is 7.3T, but the actual coercive force of Nd-Fe-B permanent magnet alloy is usually only about 1 / 3 of its theoretical value. The coercive force of the magnet can be increased by adding alloying elements to refine the grains and improving the boundary structure by tempering heat treatment process. due to Dy 2 Fe 14 B and Tb 2 Fe 14 The anisotropy fields of B are 15 and 21T, respectively, much higher than that of Nd 2 Fe 14 7.3T of B, so the most effective way to increase the coercivity o...

Claims

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Application Information

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IPC IPC(8): H01F41/02H01F1/057C25D15/00
Inventor 刘伟张鹏杰衣晓飞陈静武熊永飞黄秀莲吴玉程
Owner EARTH PANDA ADVANCE MAGNETIC MATERIAL
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