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Rare earth-iron-nitrogen system magnetic powder and method for producing same

A manufacturing method and rare earth technology, applied in metal processing equipment, transportation and packaging, etc., can solve the problems of main phase magnetization decrease, saturation magnetization decrease, magnetization decrease, etc. thermal effect

Active Publication Date: 2019-07-05
TOHOKU UNIV +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0007] However, in this case, although the heat resistance of the obtained powder is improved, there is a problem that if the coercive force is increased, the magnetization intensity will decrease.
In Non-Patent Documents 1 and 2, it is shown that the addition of elements reduces the magnetization of the main phase. The saturation magnetization of the body is 97emu / g (97Am 2 / kg), but in Example 8, as a result of the Cr increase, the coercive force becomes 7.7kOe (613kA / m) and the temperature characteristics are also improved, but the saturation magnetization is reduced to 77emu / g (77Am 2 / kg)

Method used

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  • Rare earth-iron-nitrogen system magnetic powder and method for producing same
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  • Rare earth-iron-nitrogen system magnetic powder and method for producing same

Examples

Experimental program
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Effect test

Embodiment 1

[0153] For 500 g of Sm prepared by the above method 2 Fe 17 Alloy powder, premixed 51.2g of samarium oxide with an average particle size (D50) of 2.3 μm, 4.4 g of Cr with an average particle size (D50) of 1.7 μm by a rocking mixer 2 o 3 The powder was pulverized by a media agitation mill with 1 kg of isopropanol as a solvent. The average particle size of the pulverized product observed by SEM, Sm 2 Fe 17 Alloy powder is 2.0μm, samarium oxide is 0.25μm, Cr 2 o 3 The powder is 0.09 μm.

[0154] After drying the obtained slurry under reduced pressure, the loss α after heating 50 g of the extracted mixed powder at 400° C. for 5 hours in a vacuum was measured, and it was 0.4% by mass. For all of the above mixtures, 211 g of granular calcium metal was added and mixed in an argon atmosphere, and as a reduction diffusion heat treatment, it was added in an iron crucible and heated under an argon atmosphere, kept at 880°C for 5 hours, and then kept at 950°C 0.5 hours and allowed...

Embodiment 2～5

[0161] In Example 1, the Sm pulverized by the media stirring mill 2 Fe 17 Alloy powder, samarium oxide powder, Cr 2 o 3 The average particle size of the powder and its mixing amount, the input amount of granular metal calcium, the reduction-diffusion heat treatment conditions, and the nitriding heat treatment conditions were changed as shown in Table 1, respectively, and the rare earth was prepared in the same manner as in Example 1. Iron-nitrogen-like magnetic powder.

[0162] In addition, before adding the granular metallic calcium, 50 g of the mixed powder extracted from the dried product was measured for weight loss α after heating at 400° C. for 5 hours in a vacuum. In addition, in Example 5 of Table 1, the description of reduction diffusion "800°C, 5h→840°C, 0h" means that the heater was turned off immediately after holding at 800°C for 5 hours, then raising the temperature to 840°C.

[0163] It has been confirmed that all the above powders are Th 2 Zn 17 Type crys...

Embodiment 6～8

[0165] In Example 1, the Sm after being pulverized by a media agitation mill was changed. 2 Fe 17 Alloy powder, samarium oxide powder, Cr 2 o 3 The average particle size of the powder and its mixing amount, the input amount of granular metal calcium, and the reduction-diffusion heat treatment conditions and nitriding heat treatment conditions were changed as shown in Table 1, respectively. Except for this, a rare earth iron-nitrogen magnetic powder was prepared in the same manner as in Example 1. In addition, before adding the granular metallic calcium, 50 g of the mixed powder extracted from the dried product was measured for the loss α after heating at 400° C. for 5 hours in a vacuum.

[0166] It has been confirmed that all the above powders are Th 2 Zn 17 Type crystal structure, observed by TEM, has Sm formed on the surface 2 (Fe 1-x Cr x ) 17 N y layered core-shell structure. Average particle size and residual magnetization σ of each magnetic powder r , coerciv...

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Abstract

The present invention relates to: a rare earth-iron-nitrogen system magnetic powder which has excellent heat resistance and magnetic characteristics, especially excellent coercivity and magnetization;and a method for producing this rare earth-iron-nitrogen system magnetic powder. This rare earth-iron-nitrogen system magnetic powder contains a rare earth element R, iron Fe and nitrogen N as main constituents, while having a crystal structure of Th2Zn17 type, Th2Ni17 type or TbCu7 type and an average particle diameter of from 1 mum to 10 mum (inclusive), and is characterized in that a shell layer having a thickness of 10 nm or more but less than 200 nm, which is less than 2% of the average particle diameter of the powder, is formed on the particle surfaces of the powder, said shell layer having the same crystal structure, with from 1% by atom to 20% by atom (inclusive) of Fe being substituted by Cr, and with N being contained in an amount of from 10% by atom to 20% by atom (inclusive).

Description

technical field [0001] The present invention relates to a rare earth iron-nitrogen magnetic powder excellent in heat resistance and magnetic properties, especially coercivity and magnetization, and a method for producing the same. Background technique [0002] Mainly composed of rare earth elements, iron and nitrogen, and has Th 2 Zn 17 Type, Th 2 Ni 17 Type, TbCu 7 type crystal structure of R 2 Fe 17 N x (R is a rare earth element) nitride compound is known as a magnetic material having excellent magnetic properties. [0003] Among them, Sm with Sm as R, x=3 2 Fe 17 N 3 The magnetic powder of the main phase compound is a high-performance magnetic powder for permanent magnets. Magnets are used in many ways. [0004] On the other hand, in the R 2 Fe 17 N x Nitride compound magnetic materials have a disadvantage of being poor in heat resistance (oxidation resistance). For example, the Sm of Patent Document 1 2 Fe 17 N 3 The coercive force of the magnetic pow...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B22F1/02B22F1/00B22F1/102B22F1/12
CPCB22F1/12B22F1/102H01F1/0596
Inventor 杉本谕松浦昌志石川尚米山幸伸
Owner TOHOKU UNIV
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