Explosive consolidation of Sm–Fe–N and Sm–Fe–N/(Ni, Co) magnetic powders

Chiba, Akira; Hokamoto, Kazuyuki; Sugimoto, Satoshi; Kozuka, Teruyuki; Mori, Akihisa; Kakimoto, E.

doi:10.1016/j.jmmm.2006.10.1078

Cited by 15 publications

(5 citation statements)

References 5 publications

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“…8 After etching the surfaces of the Sm-Fe-N powders with an acidic solution, they were dispersed in distilled water. Moreover, these powders were compacted at a higher density by an explosive consolidation ͑EC͒ technique using water as transmitting medium, 6,9 without a magnetic field throughout their preparation process. These ferrite/Sm-Fe-N and Sm-Fe-N powder compacting ͑PC͒ magnets were formed at 100 MPa in a magnetic field of 1.5 T by die pressing.…”

Section: Methodsmentioning

confidence: 99%

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High electrical resistance composite magnets of Sm2Fe17N3 powders coated with ferrite layer for high frequency applications

Imaoka

Koyama

Nakao

et al. 2008

Journal of Applied Physics

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This paper describes a novel type of high electrical resistance composite magnet. They were made by compacting or consolidating Sm-Fe-N powders coated with a continuous ferrite layer, which suppresses intergrain conductivity but sustains magnetic exchange interactions among grains. Sm-Fe-N powders ͑2 m in size͒ were coated with an "iron ferrite" ͑an intermediate between magnetite and maghemite͒ layer by ferrite plating, an aqueous process. They were compacted at 100 MPa to form a ferrite/SmFeN composite magnet ͑note that row Sm-Fe-N powders cannot be consolidated strongly enough to form magnets͒, and then consolidated to 92-94 vol % by the explosive consolidation technique. Coercivity and rectangularity of the compacting composite magnet decreased slightl by 2.0% and 1.4%, respectively, when compared to those of Sm-Fe-N powder compact. We also estimated the resistivity of fully dense ferrite/Sm-Fe-N magnet to be about 4000 ⍀ cm, ten times higher than the estimated value of a fully dense Sm-Fe-N magnet. Thus, the ferrite layer in our composite magnet retains magnetic exchange coupling among Sm-Fe-N grains, and yet suppresses intergrain electrical coupling to increase resistivity. This will decrease eddy current loss and improve high frequency characteristics of composite magnets.

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Section: Methodsmentioning

confidence: 99%

“…6 In permanent magnets which are used for high frequency applications, such as magnets in electrical vehicles, eddy current loss has become a large problem. 1,2 Since Sm 2 Fe 17 N 3 compounds decompose into SmN and ␣-Fe when heated above 873 K, it is fairly difficult to obtain fully dense magnets.…”

Section: Introductionmentioning

confidence: 99%

High electrical resistance composite magnets of Sm2Fe17N3 powders coated with ferrite layer for high frequency applications

Imaoka

Koyama

Nakao

et al. 2008

Journal of Applied Physics

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“…Moreover, the eutectic temperature (720 • C) of Sm-Fe alloy is higher than the decomposition temperature of Sm 2 Fe 17 N 3 . Therefore, the Sm-Fe-N magnet can only be fabricated at a low temperature by the solid-phase sintering methods [13], such as the explosive consolidation technique [14][15][16], compression shearing method [17][18][19][20], hot isostatic pressing (HIP) [21,22] and spark plasma sintering method (SPS) [13,[23][24][25][26][27].…”

Section: Introductionmentioning

confidence: 99%

Magnetic Properties and Microstructure of Ce-Cu-Al Low Melting Alloy Bonding Sm2Fe17N3 Magnet Fabricated by the Hot-Pressing Method

Zheng

Huang

et al. 2022

Magnetochemistry

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Sm2Fe17N3 compounds, having excellent intrinsic magnetic properties, are prone to decomposition at high temperatures; thus, a low melting point metal binder is the key to prepare high performance bulk magnets at low temperatures. In this paper, a new low melting point alloy Ce72Cu28-xAlx was used as the binders, and high-performance Ce-based alloy bonding Sm2Fe17N3 magnets were realized by the hot-pressing method. The experimental results demonstrated that the content of Al in the Ce-based alloys had an important influence on the performance of the magnets. High performance Sm-Fe-N bonded magnets with remanence of 10.19 KGs and maximum magnetic energy product of 21.06 MGOe were achieved by using 5 wt.% Ce72Cu22Al6 alloy as a binder. At the same time, it was found that the Ce72Cu28-xAlx alloy has a lower density and better bonding effect than the common Zn binder. Its bonding magnets still have higher performance even with extremely high oxygen content. Therefore, Ce72Cu28-xAlx alloy with low melting point is a promising new rare earth-based alloy binder. If the oxygen content of the alloy powders could be reduced, higher performance Sm2Fe17N3 bonded magnets can be prepared.

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“…Although several researchers have attempted to prepare fully dense magnets by using shock compression, aerosol deposition, hot-isostatic pressure, compression shearing, cylindrical explosive consolidation and high-pressure current sintering, [3][4][5][6][7][8] the Sm 2 Fe 17 N 3 magnets produced by those methods have not yet achieved practical application because, other than oxidation resistance, Sm 2 Fe 17 N 3 magnets do not provide any overwhelming advantages, such as high resistivity or low cost processing, over existing sintered rare-earth magnets. Thus, at present, their application is limited to resin bonded magnets.…”

Section: Introductionmentioning

confidence: 99%

Exchange coupling between soft magnetic ferrite and hard ferromagnetic Sm2Fe17N3 in ferrite/Sm2Fe17N3 composites

et al. 2016

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In our previous work, we succeeded in fabricating ferrite/Sm2Fe17N3 composite magnets from explosive-consolidating Sm2Fe17N3 powders (2μm size) which were coated with a continuous iron ferrite layer (50nm thick) in an aqueous solution. The magnetization curves had no inflection, which suggests that the soft magnetic ferrite layer is exchange-coupled with the hard ferromagnetic Sm2Fe17N3 particles. In this paper, we provide evidence of exchange coupling in ferrite/Sm2Fe17N3 composites by the following means: 1) measurements of recoil permeability, 2) detailed microstructural observation and 3) calculations of the reduction in remanence due to the introduction of a ferrite layer in the Sm2Fe17N3 magnets. Our ferrite/Sm2Fe17N3 composite magnets are a novel type of spring magnet in which an insulating soft magnetic phase is exchange-coupled with hard magnetic phase.

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Explosive consolidation of Sm–Fe–N and Sm–Fe–N/(Ni, Co) magnetic powders

Cited by 15 publications

References 5 publications

High electrical resistance composite magnets of Sm2Fe17N3 powders coated with ferrite layer for high frequency applications

High electrical resistance composite magnets of Sm2Fe17N3 powders coated with ferrite layer for high frequency applications

Magnetic Properties and Microstructure of Ce-Cu-Al Low Melting Alloy Bonding Sm2Fe17N3 Magnet Fabricated by the Hot-Pressing Method

Exchange coupling between soft magnetic ferrite and hard ferromagnetic Sm2Fe17N3 in ferrite/Sm2Fe17N3 composites

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