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Sintered neodymium-iron-boron magnet with high coercivity and low remanence temperature sensitivity, and preparation method

A high coercive force, neodymium iron boron technology, applied in the direction of magnetic objects, inductors/transformers/magnet manufacturing, magnetic materials, etc., can solve the problems of increasing the production cost of magnets, reducing the coercive force of magnets, and less natural reserves. Achieve the effect of improving the temperature stability of remanence, high coercive force and improving coercive force

Active Publication Date: 2016-12-07
SHANGHAI JIAO TONG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the use of cobalt to partially replace iron in the smelting stage of the master alloy using conventional production processes will result in a decrease in the coercive force of the magnet.
In addition, cobalt is a strategic element with few natural reserves and high price. Increasing the content of cobalt also increases the manufacturing cost of magnets

Method used

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  • Sintered neodymium-iron-boron magnet with high coercivity and low remanence temperature sensitivity, and preparation method
  • Sintered neodymium-iron-boron magnet with high coercivity and low remanence temperature sensitivity, and preparation method

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0021] 1) Arc melting alloy ingot Dy 50 Co 50 , Use an electric spark cutting machine to cut the ingot into 0.6mm thin slices, polish off the surface oxide scale with sandpaper, and clean the alloy slices with acetone ultrasonically;

[0022] 2) Process the sintered NdFeB magnet into a size of 15×15×5mm 3 Use sandpaper to polish the surface oxide layer and clean it with acetone ultrasonically;

[0023] 3) Put two pieces of Dy 50 Co 50 The alloy flakes are respectively placed on the upper and lower sides (15×15 sides) of the magnet prepared in step 2, heated to 1000℃, diffused for 4h, and then annealed at 600℃ for 2h, and the vacuum degree is 1×10 -2 Pa.

Embodiment 2

[0025] 1) Arc melting alloy ingot Dy 55 Co 45 , Use an electric spark cutting machine to cut the ingot into 0.5mm thin slices, polish off the surface oxide scale with sandpaper, and clean the alloy slices with acetone ultrasonically;

[0026] 2) Same as Step 2 of Example 1;

[0027] 3) Put two pieces of Dy 55 Co 45 The alloy flakes are respectively placed on the upper and lower sides (15×15 sides) of the magnet prepared in step 2, heated to 900℃, diffused for 1h, and then annealed at 500℃ for 6h, and the vacuum degree is 1×10 -2 Pa.

Embodiment 3

[0029] 1) Arc melting alloy ingot Dy 60 Co 40 , Use an electric spark cutting machine to cut the ingot into 0.3mm thin slices, polish off the surface oxide scale with sandpaper, and clean the alloy slices with acetone ultrasonically;

[0030] 2) Same as Step 2 of Example 1;

[0031] 3) Put two pieces of Dy 60 Co 40 The alloy flakes are respectively placed on the upper and lower sides (15×15 sides) of the magnet prepared in step 2, heated to 760℃, diffused for 8h, and then annealed at 450℃ for 1h, the vacuum degree is 6×10 -3 Pa.

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Abstract

The invention relates to a preparation method for a sintered neodymium-iron-boron magnet with high coercivity and low remanence temperature sensitivity. The preparation method comprises the steps of taking a Dy-Co alloy diffusion sheet as a diffusion source for the sintered neodymium-iron-boron magnet; performing thermal insulation at a temperature which is higher than the Dy-Co alloy melting point; and enabling the melted Dy-Co alloy liquid to be diffused to the interior of the neodymium-iron-boron magnet along grain boundary to form a Dy-rich and Co-rich composite shell-shaped structure on the edges of crystal particles. Due to the presence of the Dy-rich and Co-rich composite shell-shaped structure, the coercivity and remanence temperature stability of the sintered neodymium-iron-boron magnet can be greatly improved; compared with the prior art, the Dy-rich and Co-rich composite shell-shaped structure prepared by the method can improve the coercivity and the remanence temperature stability as well; and the sintered neodymium-iron-boron magnet which is diffused and modified by a crystal boundary diffusion process provided by the invention has the advantages of high diffusion depth of a diffusant, uniform grain boundary phase distribution, high coercivity, low magnet remanence temperature sensitivity coefficient and the like.

Description

Technical field [0001] The invention relates to a method for preparing a sintered NdFeB magnet with high coercivity and low remanence temperature sensitivity, and belongs to the technical field of rare earth permanent magnet materials. Background technique [0002] NdFeB permanent magnet materials are currently widely used in aerospace, power electronics, medical equipment, transportation and other fields due to their excellent permanent magnetic properties. In recent years, with the vigorous development of new energy industries such as wind power generation and electric vehicles, the demand for neodymium iron boron magnets that can meet high temperature applications has increased sharply. In the case of good magnet orientation, remanence and coercivity are the two main parameters that affect its magnetic energy product. As the Curie temperature of sintered NdFeB magnet is low (312°C), the temperature coefficient of remanence and coercivity is relatively large. At present, when...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01F41/02H01F1/057
CPCH01F1/0577H01F41/0293
Inventor 陈夫刚张澜庭张铁桥王静温宏远郑延董显平
Owner SHANGHAI JIAO TONG UNIV
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