• Proceedings of the Korean Magnestics Society Conference
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• 1992.10a
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• pp.26-27
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• 1992

• Journal of the Korean Magnetics Society
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• v.11 no.4
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• pp.173-178
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• 2001

The effects of heat-treatment with magnetic or non-magnetic field on magnetic properties of gas-atomized MPP dust cores subjected to various cooling processes after annealing were investigated. Upon magnetic-field annealing, ac permeability and core loss decreased with the increase of cooling rate, which were attributed to the generation of inhomogeneous internal stress and anomalous eddy current loss, respectively. It was not observed the formation of ordered phase and the related change in magnetic properties at the cooling stage for MPP dust cores. In MPP alloys, magnetic anisotropy was easily induced through the directional order, and permeability and core loss were changed under the conditions of low cooling rate and magnetic annealing.

• Journal of the Korean Magnetics Society
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• v.6 no.4
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• pp.211-217
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• 1996

The effects of Al addition to Fe-B-Nb-Cu alloy for improving the high-frequency magnetic properties and the magnetic properties of ultrathin $Fe_{78}Al_{4}Nb_{5}B_{12}Cu_{1}$ nanocrystalline alloy ribbons with the thickness less than $10\;\mu\textrm{m}$ were investigated. It was found that the effective permeability at frequencies over- 100 kHz was very high and the core loss was very low for the composition $Fe_{78}Al_{4}Nb_{5}B_{12}Cu_{1}$ alloy. Moreover, the reduction of the ribbon thickness below $10\;\mu\textrm{m}$ was very effective in improving their permeability and the core loss characteristics up to the MHz frequency range. The values of effective permeability at 1 MHz and core loss at 0.2 T, 1 MHz were 5,000 and 1.4 kW/kg, respectively. It was considered that these results were due to far refined $\alpha-Fe$ phase structure with grain size less than 10 nm and domain structure modification.

• Journal of the Korean Magnetics Society
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• v.15 no.5
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• pp.270-275
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• 2005

Dust cores (compressed powder cores) of $Fe-6.0wt\%Si$ alloy with a size of $35\~180\;{\mu}m$ in diameter have been prepared by phosphate coatings and annealings at $600\~900^{\circ}C$ for 1 h in nitrogen atmosphere. Further the magnetic and mechanical properties of the powder cores were investigated. As a general trends, the compressive strength and core loss decreased with the increase in annealing temperature. When annealed at $800^{\circ}C$, the compressive strength was 15 kgf, the permeability and quality factor were 74 and 26, respectively. Moreover the core loss at 50 kHz and 0.1 T induction was $750\;mW/cm^3$, and the percent permeability under the static field of 50 Oe was estimated to be about 78. In addition, the cut-off frequency in the cure representing the frequency dependence of effective permeability was measured to be around 200 kHz. These properties of the $Fe-6.0wt\%Si$ alloy dust cores could be considered to be due to the good insulation effect of iron-phosphate coats, the decrease in magnetocrystalline anisotropy and saturation magnetostriction and the increase in electric resistivity.

• Journal of the Korean Magnetics Society
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• v.12 no.6
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• pp.218-223
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• 2002

We investigated the magnetic properties of High Flux-type $Ni_{x}Fe_{100-x}$(x=40∼50, wt.％) permalloy powders and dust cores. The powder was prepared by conventional gas atomization in mass production scale. At the composition of $Ni_{x}Fe_{55}$, saturation magnetization was maximum. In case of lower Ni content than X=45, the $M_{s}$, decreased largely with the decrease in Ni content, which is due to the invar effect. The permeability of compressed powder cores increased with the decrease in Ni content, which was considered to be due to the decrease in the magnetostriction. In addition, the dust core with Ni=45％ showed the lowest core loss because of the increase in electrical resistivity leading to the low eddy current loss. From the better frequency dependence of permeability, larger Q value and superior DC bias characteristics of Ni=45％ than those of Ni=50％ core, it was confirmed that the 45％Ni-55％Fe powder alloy was better material for the dust core than commercial High Flux core materials.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.229-229
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• 2007

나노결정 합금재료를 전력선 통신 커플러용 자심재료로 응용하기 위해서는 고주파 대역에서의 손실 특성이 제어되어야 한다. 즉 고속 전력선 통신을 위한 자심재료의 투자율 및 완화 주파수 등의 전자기적 특성은 30MHz까지 우수하고 안정적으로 유지되어야 하며, 높은 투자율 및 자속밀도, 공진주파수뿐만 아니라 낮은 전력손실 값을 가져야 한다. 따라서 본 연구에서는 나노결점 합금 리본 표면에 딥 코팅, 졸-겔법, 진공함침 등의 방법을 이용하여 PZT, $TiO_2$ 및 $SiO_2$ 등의 산화물 고저항층을 형성시켜 자기적 성질을 유지하면서 고주파 대역의 와전류 손실을 감소시켜 통신용 자심재료로의 응용성을 향상시키고자 하였다. PZT 슬러리의 제타전위 조절을 통해 최적의 분산조건을 얻을 수 있었고, 평균 150nm인 PZT 입자의 초미립자와 가소제, 분산제, 결합제의 첨가조건을 확립할 수 있었다. 딥-코팅은 슬러리 내 유지시간 10초, 인상속도 5mm/min로 30회 반복되었을 때 가정 우수한 특성을 나타내었으며, 고주파 대역에서의 손실 감소효과를 나타내었다. 그리고 졸-겔법에 의해 제조된 슬러리를 이용한 $TiO_2$와 $SiO_2$ 산화물 저항층 코팅을 통해 금속 알콕사이드의 혼합조건 및 저항층 형성용 슬러리의 제조조건을 확립하였고, 합금 리본표면에 균일하고 우수한 점착력을 가지는 저항층을 형성시킬 수 있었으며, 이에 따른 코어손실의 감소효과를 나타낼 수 있었다. 또한 진공 함침법을 통한 저항층 형성에서, $TiO_2$ 나노분말을 표면 저항층으로 코팅했을 때, 가장 높은 코어손실 감소효과를 나타내었다. 한편, 표면 저항층이 형성된 나노결정 합금으로 제조한 자심재료를 이용하여 전력선 통신용 비접촉식 커플러에의 적용과 시험을 통해 고주파 손실 감소효과에 의한 신호전송 특성과 전류특성을 향상시킬 수 있었다.

• Journal of the Korean Magnetics Society
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• v.14 no.5
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• pp.186-191
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• 2004

The variation of magnetic properties with insulating materials(glass frits, talc and polyamide) in compressed powder cores composed of Fe$\sub$73.5/Cu$_1$Nb$_3$Si$\sub$15.5/B$\sub$7/ nanocrystalline alloy powders(size: 250～850 $\mu\textrm{m}$) and 3 wt% insulators has been investigated. Larger permeability was obtained at the frequency lower than 300～400 kHz for the powder cores including ceramic insulators(glass frits and talc) as compared to the cores with polyamide, while at higher frequency than 1 MHz the permeability of the former cores decreased rapidly. Further the cores with ceramic insulators showed larger core loss and smaller peak quality factor attained at lower frequency. On the contrary, the powder cores with polyamide exhibited high stability of permeabilities up to several MHz and superior core-loss and quality-factor properties. Moreover the dc bias property was better in the wide field range for the cores having polyamide. The enhanced magnetic properties of polyamide-added cores were attributed to the more sufficient electrical insulation between magnetic particles, where the higher insulation state was considered to be obtained from the larger volume fraction of polyamide in the powder cores.

• Journal of the Korean Magnetics Society
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• v.15 no.3
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• pp.191-197
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• 2005

In the fabrication process of Fe-based amorphous alloy powder cores by pulverization of the melt-spun ribbons and cold compaction, the effects of powder preparation method on the magnetic & electric properties, powder shapes and microstructure of cores have been investigated. The powder cores made by using rotor mill showed low effective permeability as compared to the cores prepared by ball milling. However the frequency dependence and quality factor properties were superior in the case of rotor-milling. Further the powders prepared by rotor mill had homogeneous and round shapes through strong shearing in the sieve ring, while the ball milled powders were inhomogeneous and relatively small. The lower permeability of the powder cores fabricated with rotor mill was considered to be due to the high internal stress occurred by very intensive shearing. Moreover the powder cores produced by rotor-milling showed lower core loss and good frequency dependence of effective permeability possibly due to the higher electrical insulation between magnetic particles. The dc bias property of the powder cores made by rotor-milling was better than the one by ball-milling.

• Proceedings of the Korean Magnestics Society Conference
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• 1992.03a
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• pp.24-25
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• 1992

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.228-228
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• 2007

전력선 통신용 비접촉식 커플러는 고속형(2~30 MHz)과 저속형(100~450KHz)으로 나누어 볼 수 있는데, 고속형은 현재 국내에서 독자적으로 개발되어 다양한 모델이 적용되고 있는 상황이지만, 저속형은 시작품수준으로 제조되어 있으나 신호전송 특성의 향상절구가 필요한 상황이다. 전력선 통신용 커플러는 전력선 또는 모뎀으로 통신신호를 전달하는 기능을 하는 것으로서, 전력선 통신을 위한 핵심부품이다. 따라서 본 연구에서는 100~450 KHz 대역에서 사용 가능한 저속형 비접촉식 커플러를 제조하기 위해, 권선조건, 대전류형 자심재료의 모의 해석, 노이즈 필터조건, 임피던스 매칭, 하우징방법 등의 각 공정 변수를 확립하고자 하였다. 자심재료의 모의해석에서 자심재료의 높이와 전력선 도체 단면적 변화는 자심재료의 전류포화특성에 영향을 미치지 않으며, 유효길이와 에어-갭 크기가 증가할수록 전류포화특성은 향상되는데, 자심재료의 내경이 64 mm일 때 자심재료의 폭((외경-내경)/2)은 15 mm 이상이어야 하고, 에어-갭은 약 $600\;{\mu}m$ 정도의 에어-갭을 형성시켜야함을 확인할 수 있었다. 또한 저속용 비접촉식 커플러 제조조건 실험에서 내경${\times}$외경${\times}$높이가 $64{\times}94{\times}140mm$인 자심재료를 이용하여 권선 수와 에어-갭을 각각 3회, $400{\sim}600\;{\mu}m$ 삽입했을 때, 가장 우수한 특성을 나타내었다. 그리고 저역 통과 필터를 출력부에 내장하여 통신신호 이외의 노이즈를 제거할 수 있었다. 본 연구에서 제조된 300 A급 지중선용 저속형 비접촉식 커플러는 내경${\times}$외경${\times}$높이가 $58{\times}1144{\times}158mm$이고, 100~450 KHz 통신대역에서 약$7{\pm}2dB$의 삽입손실을 나타내었다.