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Low-weight loss neodymium-iron-boron magnet and preparation method thereof

A technology of NdFeB and magnets, applied in the direction of magnetic objects, inductance/transformer/magnet manufacturing, magnetic materials, etc., can solve the problems of accelerated intergranular corrosion, accelerated oxidation, high corrosion current density, etc., to improve corrosion resistance, Improve corrosion resistance and improve the effect of corrosion weight loss

Inactive Publication Date: 2016-03-23
NINGBO STAR MATERIALS HI TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In addition, the density of the magnet is not high, and the oxide is relatively loose and the porosity is large. It is difficult to form an oxide protective film on the surface of the magnet. Once oxidized, it will cause a chain reaction and accelerate the oxidation.
And because the main phase matrix Nd of the magnet 2 Fe 14 The volume fraction of B is generally above 90%. When an electrochemical localized corrosion cell is formed, it has the characteristics of a small anode and a large cathode. The corrosion current density of the Nd-rich phase and the B-rich phase at the grain boundary is relatively large, which accelerates the intergranular corrosion. and destroy

Method used

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  • Low-weight loss neodymium-iron-boron magnet and preparation method thereof
  • Low-weight loss neodymium-iron-boron magnet and preparation method thereof
  • Low-weight loss neodymium-iron-boron magnet and preparation method thereof

Examples

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Effect test

Embodiment 1

[0035]First of all, according to the composition and mass percentage of the NdFeB magnet in Table 1, the raw materials are mixed and smelted. After the smelting is complete, it is cast into a strip. Swing the belt for hydrogen crushing and jet milling to make a powder with a particle size of 3-5 μm. Under the protection of inert gas, put the powder into the molding press mold and apply a magnetic field for orientation. After orientation, press molding, demagnetization and vacuum packaging. Put the vacuum-packed green body into the isostatic press to pressurize at 10MPa and hold the pressure for 6 minutes. Then take it out. The green body obtained after molding is put into a sintering furnace for sintering at a high temperature of 1050° C., and the sintering time is controlled at 5 hours. Then perform primary tempering at 850°C for 3 hours, then air-cool, and after air-cooling, perform secondary tempering at 550°C for 5 hours and take it out to obtain a low weight loss NdFeB m...

Embodiment 2

[0039] Firstly, according to the composition and mass percentage of the NdFeB magnet in Table 2, the raw materials are mixed and smelted. After the smelting is complete, it is cast into a strip. Swing the belt for hydrogen crushing and jet milling to make a powder with a particle size of 3-5 μm. Under the protection of inert gas, put the powder into the mold of the forming press and apply a magnetic field for orientation. After orientation, press molding, demagnetization and vacuum packaging. Put the vacuum-packed green body into the isostatic press to pressurize at 15 MPa and hold the pressure for 5 minutes. Then take it out. The green body obtained after molding is put into a sintering furnace for sintering at a high temperature of 1080° C., and the sintering time is controlled at 4 hours. Then temper once at 880°C for 3h, then air-cool, and then temper twice at 560°C for 5h after air-cooling, and then take it out to obtain a low weight loss NdFeB magnet body. Finally, the...

Embodiment 3

[0043] Firstly, according to the composition and mass percentage of the NdFeB magnet in Table 3, the raw materials are mixed and smelted. After the smelting is complete, it is cast into a strip. Swing the belt for hydrogen crushing and jet milling to make a powder with a particle size of 3-5 μm. Under the protection of inert gas, put the powder into the molding press mold and apply a magnetic field for orientation. After orientation, press molding, demagnetization and vacuum packaging. Put the vacuum-packed green body into the isostatic press and pressurize it for 5 minutes. Then take it out. The green body obtained after molding is put into a sintering furnace for sintering at a high temperature of 1100° C., and the sintering time is controlled at 4 hours. Then perform primary tempering at 900°C for 3 hours, then air cooling, and then perform secondary tempering at 560°C for 4 hours before taking out to obtain a low weight loss NdFeB magnet body. Finally, Zn metal electropl...

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Abstract

The present invention relates to a low-weight loss neodymium-iron-boron magnet and a preparation method thereof. The low-weight loss neodymium-iron-boron magnet mainly consists of the following components in percentage by mass: 27%-32.5% of Nd, 1%-1.2% of B, 2%-3% of Co, 0.15%-2.75% of alloy element M1, 0.05%-1.1% of alloy element M2, 0.7%-1.3% of rare-earth elements (excluding rare-earth element Nd), and the balance Fe. The preparation method comprises the following steps: preparing raw materials according to components of the neodymium-iron-boron magnet and mass percentages of the components; performing smelting and casting to obtain a throwing band; performing hydrogen decrepitation and jet milling to form a powder material; pressing and shaping the powder material; performing high temperature sintering and surface treatment to obtain the low-weight loss neodymium-iron-boron magnet. According to the low-weight loss neodymium-iron-boron magnet and the preparation method thereof provided by the present invention, corrosion resistance of the magnet is improved, and moreover, the protective layer formed by the metal coating and the organic coating is applied to the surface of the magnet, thereby effectively alleviating the problem of corrosion weight loss of the neodymium-iron-boron magnet.

Description

technical field [0001] The invention relates to a neodymium iron boron magnet and a preparation method thereof, in particular to a low weight loss neodymium iron boron magnet and a preparation method thereof. Background technique [0002] Sintered NdFeB magnets, as the third generation rare earth permanent magnet materials, have high performance and are widely used in energy, transportation, machinery, medical, IT, home appliances and other industries. In particular, with the development of knowledge economy represented by information technology, new uses of functional materials such as rare earth permanent magnet NdFeB industry are continuously brought, which brings a broader market prospect for NdFeB industry. [0003] In order to obtain better magnetic properties, NdFeB magnets usually consist of a thin layer of B-rich phase and Nd-rich phase and the main phase matrix Nd 2 Fe 14 B composition. The corrosion of NdFeB magnets has an important relationship with its own st...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01F1/057H01F41/02C22C38/16C22C33/02C21D6/00C23F17/00
Inventor 潘道良苏广春关井和胡剑
Owner NINGBO STAR MATERIALS HI TECH
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