Method of improving coercivity of sintering Nd-Fe-B magnetic material

A neodymium-iron-boron and magnetic material technology is applied in the field of sintered neodymium-iron-boron magnetic materials, which can solve the problems of reducing, consuming rare earth, and decreasing, and achieves the effect of ensuring high magnetic energy product, reducing average particle size and narrow particle size distribution.

Active Publication Date: 2013-04-24
ZHEJIANG ZHONGHANG NEW MATERIAL
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  • Summary
  • Abstract
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  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0009] The present invention mainly aims at the existing disadvantages of increasing the coercive force of sintered NdFeB magnets, consuming a large amount of rare earths, and reducing the magnetic moment of iron atoms due to the antiferromagnetic coupling between heavy rare earth elements and iron, which leads to the decrease of Bs and Br , provides a method for improving the coercive force of sintered NdFeB magnetic materials. The sintering step of low-temperature sintering after short-term high-temperature sintering to precipitate liquid phase improves the sintering behavior of the magnet and promotes the sintering behavior. Sintering controls grain size, inhibits grain growth, and is conducive to obtaining excellent magnetic properties such as coercive force

Method used

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  • Method of improving coercivity of sintering Nd-Fe-B magnetic material

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Embodiment 1

[0036] The retractable jet mill system of the present invention includes a bottom nozzle with an internal airflow channel and a side nozzle with an internal airflow channel. Such as figure 1 As shown, the bottom nozzle is composed of the first converging section 1, the first throat section 2 and the first diverging section 3 connected in sequence; the specific connection method is: the end of the first converging section 1 with a smaller opening and the first The sections 2 are connected, and the end of the first diffuser section 3 with a smaller opening is connected to the first throat section 2 . Such as figure 2 As shown, the side nozzle is composed of the second converging section 6, the second throat section 5 and the second diffusing section 4 which are connected in sequence; The segment 5 is connected, and the smaller opening end of the second diffuser segment 4 is connected to the second throat segment 5 .

[0037] The bottom nozzle and side nozzle structure of the...

Embodiment 2

[0039] Homogenized magnetic powder + high temperature liquid phase low temperature sintering

[0040] (1) The design composition is Nd 31 co 1 Cu 0.2 Fe 66.82 B 0.98 The quick-setting sheet is placed in a sintering furnace that can be vacuumed, vacuumed, and hydrogen gas is introduced to keep the hydrogen pressure in the sintering furnace at 5×10 5 Pa, keep it for 2 hours, keep the pressure and cool to room temperature, then vacuumize and dehydrogenate. After the vacuum degree reaches below 1kPa, start to heat up to 500°C and keep it for 3 hours for dehydrogenation.

[0041] (2) Under the protection of nitrogen, place the hydrogen powder in the jet mill of Example 1 and grind it until the average particle size of the main phase alloy powder is 3.39 μm, and the powder dispersion (D90-D10) / (2D50) is less than 0.8, Obtain magnetic powder; put the obtained magnetic powder into a powder mixing machine for powder mixing, after mixing evenly, the homogenized powder is oriented a...

Embodiment 3

[0047] Traditional grinding powder magnetic powder + high temperature liquid phase low temperature sintering

[0048] In addition to step (2) under the protection of nitrogen, the hydrogen powder is placed in the existing airflow mill with a linear airflow acceleration mechanism for grinding, and the average particle size is 3.29μm, and the powder dispersion is (D90-D10) / (2D50)= Except for the magnetic powder of 0.827, the other operations were the same as in Example 2 to obtain NdFeB magnetic materials.

[0049] The obtained NdFeB magnetic material is processed into a sample of Φ10mm×10mm, and the magnet performance is shown in Table 1.

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Abstract

The invention discloses a method of improving the coercivity of sintering Nd-Fe-B magnetic materials. The method includes the following steps of using hydrogen to crush Nd-Fe-B alloy, powder processing, compression moulding, sintering and tempering under the protection of vacuum or protective gases. The sintering condition consists of heating to 300 to 600 DEG C, keeping the temperature for 5 to 6 hours to dehydrogenize, heating once again to 1060 to 1120 DEG C, sintering for 1 to 60 minutes under high temperature, finally decreasing the temperature to 1000 to 1050 DEG C, keeping sintering for 1 to 4 hours under the temperature and cooling. The method adopts the steps of sintering for a short period under high temperature to precipitate the liquid phase and then sintering under lower temperature. The liquid phase is rapidly precipitated under high temperature, thereby improving the sintering process of the magnetic materials, promoting the performance of sintering process, controlling the grain size through sintering under lower temperature, inhabiting grain growth and benefiting obtaining an excellent coercivity of magnetic materials.

Description

technical field [0001] The invention relates to the field of sintered NdFeB magnetic materials, in particular to a method for increasing the coercive force of sintered NdFeB magnetic materials. Background technique [0002] Sintered neodymium-iron-boron (NdFeB) was born in the 1990s, and has become a kind of rare earth permanent magnet material with the highest comprehensive magnetic properties and the fastest development, because of its huge magnetic energy product (BH) max , and quickly replaced the first and second generation permanent magnet materials to become the third generation permanent magnet materials. According to the current technical research, the remanence enhancement effect of nanocomposite permanent magnet materials is obvious, but the coercive force of nanocomposite materials is too low. Therefore, for a long period of time in the future, the hard magnetic performance of sintered NdFeB permanent magnets will still rank first among permanent magnet material...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B22F3/16B22F3/10B22F9/04H01F1/057
Inventor 徐均升郭帅叶再金孙颖莉
Owner ZHEJIANG ZHONGHANG NEW MATERIAL
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