• 제목/요약/키워드: Magnetic composite materials

검색결과 177건 처리시간 0.029초

Magnetic properties of Mn54Al46C2.44/Sm2Fe17N3 and Mn54Al46C2.44/Fe65Co35 composites

  • Qian, Hui-Dong;Si, Ping-Zhan;Lim, Jung Tae;Kim, Jong-Woo;Park, Jihoon;Choi, Chul-Jin
    • Journal of the Korean Physical Society
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    • 제73권11호
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    • pp.1703-1707
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    • 2018
  • Ferromagnetic ${\tau}-phase$ $Mn_{54}Al_{46}C_{2.44}$ particles were synthesized, and its composites with commercial $Sm_2Fe_{17}N_3$ and synthesized $Fe_{65}Co_{35}$ powders were fabricated. Smaller grain size than the single domain size of the $Mn_{54}Al_{46}C_{2.44}$ without obvious grain boundaries and secondary phases is the origin for the low intrinsic coercivity. It was confirmed that the magnetic properties of the $Mn_{54}Al_{46}C_{2.44}$ can be enhanced by magnetic exchange coupling with the hard magnetic $Sm_2Fe_{17}N_3$ and soft magnetic $Fe_{65}Co_{35}$. The high degrees of the exchange coupling were verified by calculating first derivative curves. Thermo-magnetic stabilities of the composites from 100 to 400 K were measured and compared. It was demonstrated that the $Mn_{54}Al_{46}C_{2.44}$ based composites containing $Sm_2Fe_{17}N_3$ and $Fe_{65}Co_{35}$ could be promising candidates for future permanent magnetic materials with the proper control of purity, magnetic properties, etc.

Thixoforming을 위한 입자강화형 금속복합재료의 Reheating 공정 (Reheating Process of Particulates Reinforced Metal Matrix Composites for Thixoforming)

  • 이동건;안성수;강충길
    • 한국복합재료학회:학술대회논문집
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    • 한국복합재료학회 2000년도 춘계학술발표대회 논문집
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    • pp.218-223
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    • 2000
  • A both mixing process of electro-magnetic stirring and mechanical process technique were used to fabricate particulate metal matrix composites(PMMCs) for variation of particle size. The PMMCs were tested for their tensile test for with and without heat treatment with T6. PMMCs fabrication processing conditions for both electrical and mechanical process are also suggested. In order to thixoforming of PMMCs, fabricated billet are reheated by using the optimal coil designed as a function of length between PMMC billet and coil surface, coil diameter and billet length. The effect of reinforcement distribution on billet temperature variation are investigated with calculated solid fraction theory proposed as a function of matrix alloy and volume fraction of reinforcement.

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Characteristics of Shield Materials for Wireless Power Transfer

  • Chu, In Chang;Jeong, Jinseong
    • Journal of Magnetics
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    • 제19권3호
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    • pp.291-294
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    • 2014
  • In this paper, we examine the electrical and magnetic properties of three different types of shield materials used for wireless power transfer systems: namely, FeSiAl-composite, NiZn-ferrite, and FeSi-amorphous types. The power transfer efficiency and resistance of an RX coil are measured, while varying the shield thickness. For all three types, a thicker shield provides better power transfer efficiency. Analysis of the measurements shows that the FeSiAl-composite type is suitable for systems with size limitation. In terms of magnetic properties, the FeSi-amorphous type shows the best features, and is suited to high power applications. This work can be used as a guideline to select suitable shielding material in various wireless power transfer systems.

Electromagnetic Wave Absorption Characteristics of Nanocrystalline FeCuNbSiB Alloy Flakes/Polymer Composite Sheets with Different Flake Thickness

  • Lee, Tae-Gyu;Kim, Ju-Beom;Noh, Tae-Hwan
    • Journal of Magnetics
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    • 제14권4호
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    • pp.155-160
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    • 2009
  • This study examined the effects of a decrease in thickness of magnetic alloy flakes on the electromagnetic wave absorption characteristics of nanocrystalline $Fe_{73.5}Cu_1Nb_3Si_{15.5}B_7$ (at.%) alloy flakes/polymer composite sheets available for a quasi-microwave band. The thickness of FeCuNbSiB alloy flakes decreased to 1-2 $\mu$m with increasing milling time up to 24 h, and the composite sheet including alloy flakes milled for 24 h exhibited considerably enhanced power loss properties in the GHz range compared to the sheets having non-milled alloy powders. Although a considerable increase in loss factor upon milling was observed in the narrow frequency range of 4-6 GHz, there was no correlation between the complex permeability and flake thickness. However, the complex permittivity increased with increasing milling time, and there was good agreement between the milling time and the frequency dependences of the complex permittivity and power loss.

분산제에 따른 자성금속 무전해도금 기반 그래핀 분산 특성 및 복합재의 전자파 차폐 특성 연구 (Dispersion Characteristics of Magnetic Particle/Graphene Hybrid Based on Dispersant and Electromagnetic Interference Shielding Characteristics of Composites)

  • 이균배;이준식;정병문;이상복;김태훈
    • Composites Research
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    • 제31권3호
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    • pp.111-116
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    • 2018
  • 본 논문에서는 그래핀 표면에 무전해 도금을 통해 FeCoNi 자성 나노입자를 환원 성장시킨 후 이를 다양한 계면 활성제로 분산시켜 고분자 복합필름을 제조하였다. Pyridine 계면 활성제로 분산 시킨 후 제조한 복합필름은 가장 높은 분산성과 낮은 표면저항 값(351 Ohm/sq) 및 10 GHz 주파수에서 90% 이상의 전자파 차폐 능력을 보였다. 특히, 건조과정에서 pyridine의 증발은 내부 전도체 네트워크 형성과 분산성이 높은 필름 형성을 형성 할 수 있는 것으로 확인되었다.

높은 자장하에서 자기공명 영상 왜곡이 완화된 생체용 Ti 복합재료 (Bio-applicable Ti-based Composites with Reduced Image Distortion Under High Magnetic Field)

  • 김성철;김유찬;석현광;양석조;손인진;이강식;이재철
    • 대한금속재료학회지
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    • 제50권5호
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    • pp.401-406
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    • 2012
  • When viewed using a magnetic resonance imaging (MRI) system, invasive materials inside the human body, in many cases, severely distort the MR image of human tissues. The degree of the MR image distortion increases in proportion not only to the difference in the susceptibility between the invasive material and the human tissue, but also to the intensity of the magnetic field induced by the MRI system. In this study, by blending paramagnetic Ti particles with diamagnetic graphite, we synthesized $Ti_{100-x}C_x$ composites that can reduce the artifact in the MR image under the high-strength magnetic field. Of the developed composites, $Ti_{70}C_{30}$ showed the magnetic susceptibility of ${\chi}=67.6{\times}10^{-6}$, which corresponds to 30% of those of commercially available Ti alloys, the lowest reported in the literature. The level of the MR image distortion in the vicinity of the $Ti_{70}C_{30}$ composite insert was nearly negligible even under the high magnetic field of 4.7 T. In this paper, we reported on a methodology of designing new structural materials for bio-applications, their synthesis, experimental confirmation and measurement of MR images.

Vertically Aligned Carbon Film Synthesized from Magnetically Oriented Polyacetylene using Morphology Retaining Carbonization

  • Goh, Munju;Choi, Yong Mun
    • Carbon letters
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    • 제13권4호
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    • pp.226-229
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    • 2012
  • Polyacetylene (PA) films with vertically aligned fibril morphology were synthesized in homeotropic nematic liquid crystal (N-LC) solvent by using a magnetic field of 5 Tesla as an external perturbation. Scanning electron microscope (SEM) photographs indicated that the lengths of fibrils from the substrate were $5-35{\mu}m$, depending on polymerization time. Carbonization was carried out using iodine-doped PA film and a morphology-retaining carbonization method. From the SEM results, we confirmed that the vertical morphology of the PA remains unchanged even after carbonization at $800^{\circ}C$. The weight loss of the films due to carbonization at $800^{\circ}C$ is about 20% of the weight of the film before iodine doping. It is expected that vertically aligned carbon might be a precursor for preparing vertical graphite materials, which materials could be useful for electrochemical energy storage and cell electrodes.

An Application of a Magnetic Camera for an NDT System for Aging Aircraft

  • Kim, Jung-Min;Jun, Jong-Woo;Lee, Jae-Sun;Lee, Jin-Yi
    • 비파괴검사학회지
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    • 제30권3호
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    • pp.212-224
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    • 2010
  • The usefulness of the magnetic camera for non-destructive testing of aging aircraft is discussed in this paper. The magnetic camera can be used f magnetic particle testing(MT), magnetic flux leakage testing(MFLT), eddy current testing(ECT) and penetration testing(PT). It measures the distribution of a magnetic field and visualizes the magnetic pattern. Near and far side cracks, fatigue, thickness degradation, and cracks under rivets have been detected. The possibility of quantitative evaluation was also examined. Using indirect experiments, we verified the detection ability of the sensor for cracks in titanium and advanced composite materials.

Fe-Si 전기강판 폐스크랩을 이용한 연자성 분말 및 테이프 제조기술 (Manufacturing Technology for Tape Casting and Soft Magnetic Powder Using by Recycling Scrap of Fe-Si Electrical Sheet)

  • 홍원식;김상현;박지연;오철민;이우성;김승겸;한상조;심금택;김휘준
    • 마이크로전자및패키징학회지
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    • 제23권2호
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    • pp.11-18
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    • 2016
  • This study focused on examining the possibility for recycling of Fe-Si electric sheet. We manufactured Fe-6.5Si mother alloy using by Fe-Si electric sheet scrap for transformer core materials. And then, soft magnetic alloy powder which diameter and shape were $45{\sim}150{\mu}m$ and sphere type was prepared by gas atomization process. As we compared to commercial Fe-6.5Si powder, its diameter distribution and microstructure of recycled powder was a similar. To investigate the possibility of reusing the soft magnetic composite sheet for electronics, recycled powder was treated to have a high aspect ratio (AR), and we finally obtained the 65~66 AR and $2.3{\mu}m$ thickness powder. To release the residual stress of powder, heat treatment was conducted under $300{\sim}400^{\circ}C$, $N_2$ gas. And then, soft magnetic sheet was made by tape casting process using by those powders. After the density and permeability of tape was measured, and we confirmed that the recycled Fe-Si electric sheet scrap was possible to reuse the soft magnetic materials of electronics.