Neodymium-iron-boron magnet and method for regulating and controlling grain size and grain size distribution of coarse grain layer of neodymium-iron-boron magnet

A technology of grain size and particle size distribution, used in the manufacture of magnetic objects, magnetic materials, inductors/transformers/magnets, etc. The effect of narrow diameter distribution

Active Publication Date: 2020-10-09
NINGBO INST OF MATERIALS TECH & ENG CHINESE ACADEMY OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This micron-sized coarse grain is a multi-domain structure, which can lead to a substantial reduction in the coercive force of NdFeB magnets

Method used

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  • Neodymium-iron-boron magnet and method for regulating and controlling grain size and grain size distribution of coarse grain layer of neodymium-iron-boron magnet
  • Neodymium-iron-boron magnet and method for regulating and controlling grain size and grain size distribution of coarse grain layer of neodymium-iron-boron magnet
  • Neodymium-iron-boron magnet and method for regulating and controlling grain size and grain size distribution of coarse grain layer of neodymium-iron-boron magnet

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0037](1) Concentrated nitric acid solution and deionized water or ethanol are prepared into a dilute nitric acid solution with a pH of 1.3, weigh 35g of NdFeB quick-quenching powder, slowly pour it into the dilute nitric acid solution and keep stirring for pickling, pickling The washing time is 1 minute, and the oxygen content of the quick-quenching powder after pickling drops by 892ppm.

[0038] (2) Wash the acid-washed magnetic powder repeatedly with deionized water and ethanol for several times, and then put the washed magnetic powder into a drying oven for drying at a drying temperature of 70°C-80°C.

[0039] (3) Put the dried magnetic powder into a hot pressing mold M1 with an inner diameter of 16.3 mm. Put the heat press mold M1 into the vacuum induction heat press and evacuate to 5×10 -2 Pa, turn on the induction heating system for heating, and at the same time turn on the hydraulic system, and adjust the pressure acting on the mold M1 to 200MPa; when the heating temp...

Embodiment 2

[0052] According to the method of embodiment 1, the pickling time in the step (1) is changed to 5min, and the oxygen content of the quick-quenching powder drops by 862ppm after pickling. The rest of the steps remain unchanged to obtain isotropic / anisotropic NdFeB magnets. It is observed that the grains of the coarse-grained layer of the obtained magnet are the same as in Example 1, and the grains are obviously refined and the grain size distribution is narrowed.

Embodiment 3

[0054] According to the method for embodiment 1, the pH of the dilute nitric acid solution is 1 in the step (1), and the oxygen content of the quick-quenching powder drops by 732ppm after pickling. The rest of the steps remain unchanged to obtain isotropic / anisotropic NdFeB magnets. It is observed that the grains of the coarse-grained layer of the obtained magnet are the same as in Example 1, and the grains are obviously refined and the grain size distribution is narrowed.

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Abstract

The invention relates to the technical field of rare earth permanent magnet materials, and discloses a method for regulating the grain size of a coarse grain layer of a neodymium-iron-boron magnet. The method comprises the following steps of: performing acid pickling treatment on rapidly-quenched neodymium-iron-boron magnetic powder by using an acid solution, conducting washing, and performing hotpressing to prepare an isotropic neodymium-iron-boron magnet and an anisotropic neodymium-iron-boron magnet. According to the method, the grain size of an interface coarse grain layer in the neodymium-iron-boron magnet can be effectively reduced by reducing the oxygen content of the surface of the rapidly-quenched neodymium-iron-boron magnetic powder through acid and strictly controlling the pH value of the acid solution and acid pickling time, so narrow particle size distribution is obtained, which has a good effect on improving the residual magnetism and coercive force of the magnet.

Description

technical field [0001] The invention relates to the technical field of rare earth permanent magnet materials, in particular to a neodymium-iron-boron magnet and a method for controlling the grain size and grain size distribution of the coarse-grained layer of the neodymium-iron-boron magnet. Background technique [0002] As a third-generation rare earth permanent magnet material, neodymium iron boron (Nd-Fe-B) is widely used in communication, computer, aerospace, transportation, automobile industry and other fields. Hot pressing / hot deformation technology is one of the main methods to prepare full-density and high-anisotropy NdFeB rare earth permanent magnet materials. Compared with the currently commonly used sintering technology, this technology has the advantages of short process flow, less rare earth consumption, no need for external magnetic field orientation, and easy realization of near-net molding. From the perspective of microstructure, the NdFeB thermally deformab...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01F41/02H01F1/057
CPCH01F41/0253H01F41/0266H01F41/0273H01F1/0576
Inventor 都业源陈仁杰尹文宗唐旭剧锦云闫阿儒
Owner NINGBO INST OF MATERIALS TECH & ENG CHINESE ACADEMY OF SCI
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