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Method for improving coercive force of sintered rare earth-iron-boron permanent magnetic material

A permanent magnet material and coercive force technology, applied in the direction of magnetic material, inorganic material magnetism, metal material coating process, etc., can solve the problem that the magnet is difficult to obtain the diffusion effect, achieve good application prospects, reduce the reduction of remanence, significant effect

Inactive Publication Date: 2012-10-24
NINGBO INST OF MATERIALS TECH & ENG CHINESE ACADEMY OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the current grain boundary diffusion method is limited by ultrasonic coating of heavy rare earth elements on the surface of the magnet. Due to the limitation of the coating amount of heavy rare earth elements, it is difficult to obtain a good diffusion effect for larger-sized magnets.

Method used

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  • Method for improving coercive force of sintered rare earth-iron-boron permanent magnetic material
  • Method for improving coercive force of sintered rare earth-iron-boron permanent magnetic material
  • Method for improving coercive force of sintered rare earth-iron-boron permanent magnetic material

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0022] In this embodiment, the molecular formula representing the composition and mass percentage of the sintered rare earth-iron-boron permanent magnet material is Nd 30 Fe 69 B 1 . The preparation method of the sintered rare earth-iron-boron permanent magnet material is as follows.

[0023] Alloy composition into Nd by quick-setting flake technology 30 Fe 69 B 1 (mass percentage content) of the main alloy is made into quick-setting flakes, and then it is made into a powder with an average particle size of 3.0 microns by hydrogen crushing and jet milling processes. The powder was subjected to secondary orientation pressing in a 2 T magnetic field, and cold isostatic pressing at a pressure of 300 MPa for 60 seconds. The compact was then placed in a vacuum furnace and sintered at 1040 °C for 2 hours. Finally, the sintered permanent magnet material was processed into a size of Φ10mm×10mm to obtain a test sample.

[0024] The test sample was tested for performance, and it...

Embodiment 2

[0035] In this example, the test sample prepared in Example 1 is used.

[0036] A group of samples, Sample C, was taken out of the above test samples and subjected to heat treatment.

[0037] The heat treatment process of sample C is as follows: sample C is buried in the same DyH as in Example 1 x In the powder, heat treatment in vacuum at 800°C for 4 hours, and test its properties after heat treatment, as shown in the table below.

[0038] Then, sample C was placed in a sintering furnace, and subjected to vacuum heat treatment at 500° C. for 2 hours, and the properties of sample C were tested after heat treatment, as shown in Table 2 below.

[0039] Table 2: Magnet properties after heat treatment at 800°C

[0040]

[0041] Combining the above tables 1 and 2, it can be seen that the coercive force of sample C is increased from 10.56kOe before heat treatment to heat treatment (DyH x Atmosphere 800℃ heat treatment + vacuum heat treatment) to 14.16kOe, an increase of 34.1%; w...

Embodiment 3

[0043] In this example, the test sample prepared in Example 1 is used.

[0044] A group of samples, Sample D, was taken out of the above test samples and subjected to heat treatment.

[0045] The heat treatment process of sample D is: sample D is buried in the same DyH in embodiment 1 x In the powder, heat treatment in vacuum at 700°C for 4 hours, and test its properties after heat treatment, as shown in the table below.

[0046] Then, sample D was placed in a sintering furnace, and subjected to vacuum heat treatment at 500° C. for 2 hours, and the properties of sample D were tested after heat treatment, as shown in Table 2 below.

[0047] Table 3: Magnet properties after heat treatment at 700°C

[0048]

[0049] Combining the above tables 1 and 3, it can be seen that the coercive force of sample D is increased from 10.56kOe before heat treatment to heat treatment (DyH x Atmosphere 700℃ heat treatment + vacuum heat treatment) to 13.74kOe, an increase of 30.1%; while the ...

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Abstract

The invention provides a method for improving the coercive force of a sintered rare earth-iron-boron permanent magnetic material. According to the method, the sintered rare earth-iron-boron permanent magnetic material is buried in hydride powder of pure rare earth or mixed rare earth, and the mixture is subjected to a vacuum heat treatment; the heat treatment is carried out for 1-20h under a temperature of 700-1000 DEG C, and the mixture is naturally cooled to room temperature; the sintered rare earth-iron-boron permanent magnetic material is fetched and placed in a heat treatment furnace; and the material is subjected to vacuum heat treatment for 1-5h under a temperature of 450-600 DEG C. According to prior arts, heavy rare earth elements are coated on the surface of a magnet through ultrasonic coating, and rare earth element grain boundary diffusion is realized, such that the coercive force of the permanent magnetic material is improved. Compared the with prior arts, according to the invention, the heavy rare earth elements can be continuously obtained from the surrounding powder, such that sufficient heavy rare earth element resource is ensured. Therefore, the method provide by the invention is suitable for sintered rare earth-iron-boron permanent magnetic materials with relatively large dimensions. On a basis that residual magnetism is maintained unchanged, the coercive force of the treated sintered rare earth-iron-boron permanent magnetic material is substantially improved.

Description

technical field [0001] The invention relates to a method for increasing the coercive force of a sintered rare earth-iron-boron permanent magnet material, which belongs to the field of magnetic materials. Background technique [0002] As a typical representative of rare earth permanent magnet materials, rare earth-iron-boron sintered permanent magnet materials are the best permanent magnet materials currently used, especially sintered NdFeB permanent magnet materials. Since its development, it has been widely used in many fields such as computer industry, automobile industry, communication information industry and medical transportation field, and has made the application of some small, highly integrated high-tech products possible. However, the coercive force of rare earth-iron-boron sintered permanent magnet materials is relatively low, which limits the application of such materials in many fields, such as electric vehicles, hybrid vehicles, and wind power generation. Howe...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C23C10/34C23F17/00H01F1/053H01F1/08
Inventor 刘友好郭帅刘兴民李东闫阿儒
Owner NINGBO INST OF MATERIALS TECH & ENG CHINESE ACADEMY OF SCI
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