Rare earth magnet and manufacturing method thereof

A magnet and rare earth technology, applied in the field of rare earth magnets and their manufacture, can solve the equal problems of no fluorine compound, it is difficult to achieve a low concentration of rare earth elements with magnetic properties, and it is difficult to form fluorine, and achieves high magnetic flux density, low The effect of coercive force and low iron loss

Inactive Publication Date: 2008-10-01
HITACHI LTD
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  • Abstract
  • Description
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  • Application Information

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Problems solved by technology

For this reason, it is difficult to improve magnetic properties or lower the concentration of rare earth elements in magnetic powder whose magnetic properties deteriorate at a temperature lower than that of sintered magnets because the heat treatment temperature necessary for diffusion is high.
[0009] In the above-mentioned Patent Documents 1-5, since the fluorine compound used in the treatment is powder or a mixture of powder and solvent, it is difficult to effectively form a fluorine-containing phase along the surface of the magnet powder.
In addition, in the above-mentioned conventional method, the fluorine compound used in the treatment is in point contact with the surface of the magnetic powder, and the phase containing fluorine is not easily in surface contact with the magnetic powder. Therefore, more than necessary processing raw materials and heat treatment at high temperature are required.
In addition, there is no description about iron in the fluorine compound, and there is no description about the content of iron in the fluorine compound.

Method used

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  • Rare earth magnet and manufacturing method thereof

Examples

Experimental program
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Effect test

Embodiment 1

[0041] Made as NdFeB powder with Nd 2 Fe 14 B-based quenching powders form fluorine compounds on their surfaces. Formation of DyF on the surface of quenched powder 3 In the case of Dy(CH 3 COO) 3 with H 2 O dissolved and HF was added. Gelatin-like DyF can be formed by adding HF 3 ·XH 2 O or DyF 3 ·X(CH 3 COO) (X is a positive number). This was centrifuged, the solvent was removed, and it was mixed with the above-mentioned NdFeB powder as a translucent solution. The solvent of the mixture was evaporated, and the water of hydration was evaporated with heating. The coating film thus formed was studied by XRD. As a result, when the heating temperature is lower than 200° C., the half width of the X-ray diffraction peak is twice or more than the peak width after the subsequent heat treatment, including a broad peak. The half-value width of this broad peak is 1 degree or more. By heat treatment at a temperature higher than 200°C, the crystal structure of the fluorine co...

Embodiment 2

[0043] Made as NdFeB powder with Nd 2 Fe 14 B-based quenching powders form fluorine compounds on their surfaces. Formation of DyF on the surface of quenched powder 3 In the case of Dy(CH 3 COO) 3 with H 2 O dissolved and HF was added. Gelatin-like DyF can be formed by adding HF 3 ·XH 2 O. It was centrifuged and the solvent was removed. The concentration of rare earth fluoride in the gel state is 10g / dm 3 As mentioned above, the transmittance of the treatment liquid with an optical path length of 1 cm at a wavelength of 700 nm is 5% or more. This light-transmitting solution is mixed with the above-mentioned NdFeB powder. The solvent of the mixture was evaporated, and the water of hydration was evaporated with heating. It was found that by heat treatment at 500°C, the crystal structure of the fluorine compound was changed from NdF 3 Structure, NdF 2 structure etc.

[0044] The cross-section of the heat-treated magnetic powder was observed with a transmission elect...

Embodiment 3

[0051] The rare earth fluoride or alkaline earth metal fluoride coating film forming treatment liquid is obtained by dissolving rare earth acetate or alkaline earth metal acetate in water, and then gradually adding diluted hydrofluoric acid. The solution of the fluorine compound or the oxyfluorine compound or the oxyfluorocarbon that produced the gel-like precipitate was stirred using an ultrasonic stirrer, and after centrifugation, methanol was added, and after stirring the gel-like methanol solution, the anion was removed and the Its transparent. Anions are removed until the transmittance of the treatment solution under visible light reaches 5% or more. This solution was coated on magnetic powder, and the solvent was removed. Made as NdFeB powder with Nd 2 Fe 14 B-based quenching powders form Dy fluorine compounds on their surfaces. After mixing the above-mentioned translucent solution with the above-mentioned NdFeB powder, the solvent of the compound was evaporated. By...

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Abstract

A structure of a magnet wherein a magnet consisting of a magnetic body including iron and rare earths, a plurality of fluorine compound layers or oxyfluorine compound layers are formed interior of the magnetic body, and the fluorine compound layer or oxyfluorine compound layer has a major axis which is greater than the mean particle size of the crystal grains of the magnetic body.

Description

technical field [0001] The present invention relates to a rare-earth magnet and a manufacturing method thereof, in particular to a magnet having high energy product or high heat resistance and a manufacturing method thereof by reducing the amount of heavy rare-earth elements used. Background technique [0002] In recent years, in order to improve the characteristics of magnets, development research has been conducted on the structure of rare earth magnets containing fluorine compounds or oxyfluorine compounds. For example, Patent Documents 1 to 5 below disclose techniques for forming a fluorine-containing phase on the surface of a magnet using a powdered fluorine compound or a mixture of a powdered fluorine compound and a solvent. [0003] Patent Document 1 JP-A-2003-282312 [0004] Patent Document 2 JP-A-2006-303436 [0005] Patent Document 3 JP-A-2006-303435 [0006] Patent Document 4 JP-A-2006-303434 [0007] Patent Document 5 JP-A-2006-303433 [0008] In the prior a...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01F1/053H01F1/057H01F1/08
Inventor 小室又洋佐通祐一森下芳伊舟生重昭片寄光雄
Owner HITACHI LTD
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