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r-t-b series sintered magnet

A R-T-B, sintered magnet technology, applied in inductor/transformer/magnet manufacturing, magnetic objects, magnetic materials, etc., can solve the problem of reducing the maximum energy product, and achieve the effect of improving the residual magnetic flux density and coercive force

Active Publication Date: 2020-08-14
TDK CORPARATION
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] In the above-mentioned single alloy method, the maximum energy product (Maximum Energy Product) sometimes decreases due to the presence of heavy rare earth elements in the main phase particles.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0140] After processing the sintered magnet obtained by the above steps into a rectangular parallelepiped with a width of 20 mm, a length of 20 mm, and a thickness of 5 mm in the orientation direction, it was kept at 750° C. for 10 minutes in an atmosphere of 5 vol % hydrogen and 95 vol % Ar. , to decompose and disproportionate the main phase particles that mainly exist in the surface layer of the magnet.

[0141] Next, TbH was applied to the entire surface of the sintered magnet so that the weight of Tb became 0.5% by weight relative to the weight of the sintered magnet. 2 A slurry in which particles (average particle diameter D50 = 5 μm) was dispersed in ethanol was used to allow Tb to adhere. After coating the slurry, heat treatment was performed at 770° C. for 5 hours while flowing Ar under atmospheric pressure, and then heat treatment was performed at 950° C. for 5 hours to diffuse Tb grain boundaries.

[0142] After the above heat treatment, quench with a cooling rate o...

Embodiment 2

[0146] The sintered magnet obtained by the above steps was kept at 700° C. for 10 minutes in an atmosphere of 8 vol % CO and 92 vol % Ar to decompose and disproportionate the main phase particles mainly present in the surface layer of the magnet.

[0147] Next, the TbH 2 A slurry in which particles (average particle diameter D50 = 5 μm) was dispersed in ethanol was used to allow Tb to adhere. After coating the above slurry, heat treatment was performed at 770° C. for 5 hours while flowing Ar under atmospheric pressure, and then heat treatment was performed at 950° C. for 5 hours to diffuse Tb grain boundaries.

[0148] After the above heat treatment, quench at a cooling rate of 200°C / min, and make R from the liquid phase 2 T 14 B crystallization and recrystallization.

[0149] Thereafter, a re-aging treatment was performed at 500° C. for 1 hour in an Ar atmosphere and atmospheric pressure.

[0150] The magnetic characteristics (residual magnetic flux density Br, coercive f...

Embodiment 3

[0152] The sintered magnet obtained through the above-mentioned procedure was placed in N 2 In an atmosphere of 8% by volume and 92% by volume of Ar, the temperature was maintained at 650° C. for 30 minutes to decompose and disproportionate the main phase particles mainly present in the surface layer of the magnet.

[0153] Next, the TbH 2A slurry in which particles (average particle diameter D50 = 5 μm) was dispersed in ethanol was used to allow Tb to adhere. After coating the above slurry, heat treatment was performed at 770° C. for 5 hours while flowing Ar under atmospheric pressure, and then heat treatment was performed at 950° C. for 5 hours to diffuse Tb grain boundaries.

[0154] After the above heat treatment, quench at a cooling rate of 200°C / min, and make R from the liquid phase 2 T 14 B crystallization and recrystallization.

[0155] Thereafter, a re-aging treatment was performed at 500° C. for 1 hour in an Ar atmosphere and atmospheric pressure.

[0156] The m...

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Abstract

An R-T-B based sintered magnet including a plural number of main phase particles having an R2T14B type crystal structure. R is at least one rare earth element essentially including heavy rare earth elements RH, T is at least one transition metal element essentially including Fe or Fe and Co, and B is boron. At least one of the main phase particles is a reverse core-shell main phase particle including a core part and a shell part, in which CRC / CRS>1.0 is satisfied when a total RH concentration (at %) in the core part is defined as CRC and a total RH concentration (at %) in the shell part is defined as CRS. An existence ratio of the reverse core-shell main phase particles is larger in a surface layer part of the magnet than in a central part of the magnet.

Description

technical field [0001] The invention relates to an R-T-B series sintered magnet. Background technique [0002] As shown in Patent Document 1, it is known that R-T-B based sintered magnets have excellent magnetic properties. Currently, it is desired to further improve the magnetic characteristics. [0003] As a method of improving the magnetic properties of R-T-B based sintered magnets, especially the coercive force, there is known a method (single alloy method) in which a heavy rare earth element is contained as R at the stage of producing a raw material alloy. In addition, there is also a method of pulverizing a main phase alloy not containing a heavy rare earth element and a grain boundary phase alloy containing a heavy rare earth element, followed by mixing and sintering (two-alloy method). Furthermore, as described in Patent Document 2, there is a method (grain boundary diffusion method) of diffusing heavy rare earth elements through grain boundaries by attaching heavy...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01F1/057H01F41/02
CPCH01F1/0577H01F41/0253H01F41/0266H01F41/0293C22C38/005
Inventor 藤川佳则三轮将史
Owner TDK CORPARATION