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Method for improving corrosion resistance of neodymium-iron-boron waste recycled magnet

A technology of waste recycling and NdFeB, applied in the direction of magnetic objects, magnetic materials, inductors/transformers/magnets, etc., can solve the problems of magnet main phase grain shedding, electrochemical corrosion, magnet corrosion, etc., to achieve uniform distribution, Effect of improving corrosion resistance and improving utilization rate

Pending Publication Date: 2021-01-12
HANGZHOU DIANZI UNIV
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  • Abstract
  • Description
  • Claims
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Problems solved by technology

However, since Nd-Fe-B (Nd-Fe-B) magnets have a multi-phase structure, especially the Nd (Nd)-rich phase, the Nd (Nd) element is very active, and it is very easy to react with oxygen and water in the air. Corrosion, and because the electrode potential of the Nd-rich (neodymium) phase is quite different from the electrode potential of the main phase, it is very easy to form a primary battery in a corrosive environment, and electrochemical corrosion occurs, which accelerates the corrosion of the magnet and eventually leads to the crystallization of the main phase of the magnet. Therefore, improving the corrosion resistance of Nd-Fe-B (Nd-Fe-B) magnets is an important topic in the study of Nd-Fe-B

Method used

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  • Method for improving corrosion resistance of neodymium-iron-boron waste recycled magnet
  • Method for improving corrosion resistance of neodymium-iron-boron waste recycled magnet
  • Method for improving corrosion resistance of neodymium-iron-boron waste recycled magnet

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Experimental program
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Effect test

Embodiment 1

[0022] Step 1), with N35SH brand (H cj : 19~20kOe, (BH) max : 34~35MGOe, B r : 11 ~ 12kGs) NdFeB magnet as the main alloy, take the NdFeB magnet with a mass ratio of 99.7%, and carry out hydrogen cracking treatment at 590°C and 0.6MPa hydrogen pressure. After dehydrogenation, the mass ratio 0.3% copper powder with an average particle size of 1 μm was subjected to jet milling at a speed of 5000 rpm to prepare mixed magnetic powder with an average particle size of 3 μm.

[0023] Step 2), the mixed powder is subjected to compression molding orientation under a 2T orientation magnetic field, and then cold isostatic pressing under a pressure of 200MPa to obtain a green body of a magnet;

[0024] Step 3), sintering the obtained magnet green body at 1040°C for 2h, then heat-treating at 850°C for 3h in the next step, and then heat-treating in the second step at 550°C for 4h, to obtain a NdFeB grain boundary reconstructed magnet;

[0025] The weight loss data of the obtained grain b...

Embodiment 2

[0035] Step 1), with 38H grade (H cj : 15~18kOe, (BH) max : 35~38MGOe, B r: 12 ~ 13kGs) NdFeB magnets as the main alloy, take NdFeB magnets with a mass ratio of 99.8%, and carry out hydrogen cracking treatment at 590 ° C and 0.6 MPa hydrogen pressure. After dehydrogenation, the mass ratio 0.2% of copper powder with an average particle size of 1 μm is subjected to jet milling, and the jet mill speed is 5000 rpm to prepare mixed magnetic powder with an average particle size of 3 μm;

[0036] Step 2), the mixed powder is subjected to compression molding orientation under a 2T orientation magnetic field, and then cold isostatic pressing under a pressure of 200MPa to obtain a green body of a magnet;

[0037] Step 3), sintering the obtained magnet green body at 1040°C for 2h, then heat-treating at 850°C for 3h in the next step, and then heat-treating in the second step at 550°C for 4h, to obtain a NdFeB grain boundary reconstructed magnet;

[0038] The weight loss data obtained b...

Embodiment 3

[0047] Step 1), with N40 brand (H cj : 10~15kOe, (BH) max : 38~40MGOe, B r : 12~13kGs) NdFeB magnets as the main alloy, take the NdFeB magnets with a mass ratio of 99.9%, and carry out hydrogen cracking treatment at 590°C and 0.6MPa hydrogen pressure. After dehydrogenation, the mass ratio 0.1% of copper powder with an average particle size of 1 μm is subjected to jet milling at a speed of 5000 rpm to prepare mixed magnetic powder with an average particle size of 3 μm;

[0048] Step 2), the mixed powder is subjected to compression molding orientation under a 2T orientation magnetic field, and then cold isostatic pressing under a pressure of 200MPa to obtain a green body of a magnet;

[0049] Step 3), sintering the obtained magnet green body at 1040°C for 2h, then heat-treating at 850°C for 3h in the next step, and then heat-treating in the second step at 550°C for 4h, to obtain a NdFeB grain boundary reconstructed magnet;

[0050] The weight loss data obtained by exposing th...

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Abstract

The invention discloses a method for improving the corrosion resistance of a neodymium-iron-boron waste recovery magnet, which comprises the following steps: carrying out hydrogen decrepitation on sintered neodymium-iron-boron waste recovery again, and mixing copper powder with the size of 1 mu m for jet mill grinding. Due to the introduction of the copper powder, not only is the distribution of grain boundary structures changed, but also the phase composition of the grain boundary structures is changed, so that the magnetic property and the corrosion resistance of the neodymium iron boron waste recovery magnet are improved at the same time. NdFeB waste is used for recovering magnet raw materials and comes from the production process of NdFeB commercial magnets, and needed equipment is a hydrogen breaking furnace and an airflow powder grinding machine. According to the method, the advantages of a double-alloy process and a grain boundary modification technology are combined, the resource utilization rate of the neodymium iron boron is effectively increased while the magnetic performance and the corrosion resistance are guaranteed, recycling of the neodymium iron boron waste recycled magnet in the production process is promoted, and economic benefits can be better played.

Description

technical field [0001] The invention belongs to the technical field of anti-corrosion magnets, and relates to a method for improving the anti-corrosion performance of magnets recovered from NdFeB waste materials. Background technique [0002] NdFeB permanent magnet has the characteristics of high remanence, high coercive force and high magnetic energy product. It is the rare earth permanent magnet material with the best comprehensive performance and the widest application range. It is widely used in medical treatment, electronic products, and new energy vehicles. and wind power generation. In 2017, the output of China's sintering market was 104,000 tons, and the output of the global sintering market was 120,000 tons. WTGs predict that the average annual demand growth rate of NdFeB will increase by 10% during 2020-2030. These data show that NdFeB permanent magnet materials will have a high market demand in the future, and China's NdFeB production has a high share, which pro...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01F1/057H01F41/02
CPCH01F1/0577H01F1/0573H01F41/0253H01F41/0266
Inventor 张雪峰潘猛杰刘孝莲李智赵利忠刘先国
Owner HANGZHOU DIANZI UNIV
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