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

A magnetic material, neodymium iron boron technology, applied in the field of sintered neodymium iron boron magnetic materials, can solve the problems of reduction, rare earth consumption, and drop, and achieve the effect of ensuring high magnetic energy product, reducing average particle size, and narrow particle size distribution

Active Publication Date: 2015-04-29
ZHEJIANG ZHONGHANG NEW MATERIAL
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  • Summary
  • Abstract
  • Description
  • 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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Embodiment 1

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

Embodiment 2

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

[0040] (1) The design component 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 evacuated, vacuumed, and hydrogen is introduced to keep the hydrogen pressure in the sintering furnace at 5 × 10 5 Pa, maintained for 2 hours, kept the pressure and cooled to room temperature and then dehydrogenated by vacuum. After the vacuum degree reached below 1 kPa, the temperature was raised to 500 ° C and kept for 3 hours for dehydrogenation. After the dehydrogenation was completed, it was cooled to room temperature to obtain hydrogen breakdown.

[0041] (2) Under the protection of nitrogen, place the hydrogen crusher in the jet mill of Example 1 to grind 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 the magnetic powder; put the obtained mag...

Embodiment 3

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

[0048] Except for step (2), under the protection of nitrogen, the hydrogen crushed material is placed in an existing jet mill with a linear gas flow acceleration mechanism, and the average particle size is 3.29 μm, and the powder dispersion is (D90-D10) / (2D50)= Except for the magnetic powder of 0.827, the rest of the operations are the same as those in Example 2, and the NdFeB magnetic material is obtained.

[0049] The obtained NdFeB magnetic material is processed into a sample of Φ10mm×10mm, and the magnet properties are 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 neodymium iron boron magnetic materials, in particular to a method for improving the coercive force of sintered neodymium iron boron magnetic materials. Background technique [0002] Sintered neodymium iron boron (NdFeB) was born in the 1990s, and has become a rare earth permanent magnet material with the highest comprehensive magnetic performance 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 coercivity of nanocomposite materials is too low. Therefore, for a long period of time in the future, the hard magnetic properties of sintered NdFeB permanent magnets will still rank first in the list of...

Claims

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Application Information

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Patent Type & Authority Patents(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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