유한요소해석을 이용한 표면적용을 위한 자기 복합재료의 설계

김승호(Seung-Ho Kim),H. Thomas Hahn,허훈(Hoon Huh) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.5

The present paper explores the use of magnetic composites reinforced by permanent magnetic particles for a number of surface applications including adhesive joints, coatings and reduced-friction surfaces. When magnetic composites are used as an adhesive with magnetically permeable adherends, the composite can provide additional bonding stresses through magnetic attraction. The same benefits are expected when the composite is coated on magnetic surfaces. Composite coatings can also be used to create reduced-friction surfaces through magnetic repulsion. In this paper, a finite element method has been used to design the magnetic composite. Magnetic characteristics of magnetic composites are calculated through electromagnetic finite element analysis. The design parameters are the morphology, spatial distribution, size and volume fraction of magnet particles. Design time and costs in the development stage of composites can be minimized through optimized process conditions calculated from finite element simulations.

Effect of Magnetic Field on the Dielectric Properties of Multiferroic Composites

Ravindar Tadi,김용일,류권상,김철기 한국물리학회 2012 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.61 No.9

Magneto-dielectric materials were a subject of potential interests in terms of basics research and new device applications. In this study, 0.5BaTiO<SUB>3</SUB>-0.5MgFe<SUB>2</SUB>O<SUB>4 </SUB> composites with ferroelectric and soft magnetic properties, synthesized using wet chemical methods were investigated for the possibility of controlling the dielectric properties by application of magnetic field. Composite pellets were thermally treated in air at 950 to 1150 ℃ for 3 h and characterized for structural, magnetic and magnetic-dielectric properties. All the composites showed soft magnetic properties. Magnetic field was applied to composite pellets in the order of 200 to 400 Oe and variation of dielectric constant was observed. Significant findings such as the increase of dielectric constant with increase of magnetic field were observed in the composite pellets. The increase in dielectric constant with respect to applied magnetic field was depicted as an effect of increased magnetostriction of the magnetic phase.

Preparation and characterization of flaky FeSiAl composite magnetic powder core coated with MnZn ferrite

Zhen Wang,Xiansong Liu,Xucai Kan,Ruiwei Zhu,Wei Yang,Qiuyue Wu,Shengqiang Zhou 한국물리학회 2019 Current Applied Physics Vol.19 No.8

The flattening of FeSiAl soft magnetic powder was achieved by ball milling process, and MnZn/FeSiAl composite magnetic powder core was prepared by press molding. The effect of different coating amount of MnZn ferrite on the soft magnetic properties of FeSiAl was studied. At the same time, the optimal stress-relieving annealing temperature of the composite magnetic powder core is revealed. The results showed that the addition of MnZn ferrite affected the magnetic properties such as saturation magnetization (Ms), initial permeability (μi) and power loss (Pcm) of FeSiAl soft magnetic. With the increase of MnZn ferrite addition content, the saturation magnetization of composites decreased gradually, and the magnetic permeability increased first and then decreased, and the loss decreased first and then increased. When the addition content of MnZn ferrite was 5%, the permeability reached the maximum, which was 28.1% higher than that of the pure FeSiAl magnetic powder core under the same conditions. At the same time, the loss was the lowest, which was 13.3% lower than the pure FeSiAl powder core under the same conditions. When the annealing temperature is around 650 °C, the magnetic powder core has the largest magnetic permeability and the lowest loss.

복합초전도체의 자기적 임계온도 측정의 표준화연구

이규원,김문석,김동호,이상근,Lee K. W,Kim M. S,Kim D. H,Lee S. G 한국초전도학회 2004 Progress in superconductivity Vol.6 No.1

Magnetic $T_{c}$ of composite superconductors has been studied for providing a standard method. Various magnetization-temperature curves of NbTi, $Nb_3$Sn and Bi-2223 wires were measured using a SQUID magnetometer. Magnetization-temperature curve of zero-field-cooled procedure showed larger values than fie Id-cooled procedure. To obtain higher resolution near the onset temperature, we employed a two-field-direction method which measures a magnetization-temperature curve of a specimen first in positive and then negative fields. Analytical comparison of the magnetic $T_{c}$, with the resistive T$_{c}$ was accomplished for three specimens. The magnetic $T_{c}$/ mettled showed more detailed information on superconducting state of a specimen than the resistive$T_{c}$/ method. We have also studied the field dependence of the magnetic $T_{c}$ from 5 Oe to 120 Oe, however, no significant difference on field strength was found in our three specimensns

In vivo Acute Cytotoxicity Study of Poly(2-amino ethyl methacrylateco- methylene bis-acrylamide) Magnetic Composite Synthesized in Supercritical CO2

Gunjan Bisht,M. G. H. Zaidi,Biplab KC 한국고분자학회 2018 Macromolecular Research Vol.26 No.7

With magnetic ferrite nanoparticles (FNPs) gaining interest in biotechnological fields and methacrylates being used as synthetic polymer for therapeutics loading and conjugation, we attempt to make novel magnetic composite by supercritical CO2 assisted entrapment of FNPs into in situ synthesized polymeric mesh of 2-amino ethyl methacrylate (AEMA) cross linked with methylene bis-acrylamide (MBA) at90±1 oC and pressure of 1200 psivia 2,2-azobisisobutyronitrile (AIBN) initiated radical polymerization. Particle thus obtained was characterized by using proton nuclear magnetic resonance (1H NMR), X-ray diffraction (XRD), thermal gravimetric-derivative thermogravimetric-differential thermal analysis (TG-DTGDTA), atomic force microscopy (AFM), and vibrating sample magnetometer (VSM). 1H NMR of Copolymer (without FNPs embedded) demonstrated distinct peaks verifying AEMA moieties flanked by MBA moieties with free amino group. Though the particle showed less saturation magnetization than that of as synthesized FNPs, it still maintained similar magnetic profile. AFM results showed average grain size of polymeric magnetic composites (PMCs) to be 80 nm with less agglomeration. TGA results verify the thermal stability of the compound upto 200 oC. In vivo acute cytotoxicity was profiled by administrating four different concentrations of FNPs, Copolymer and PMCs (FNPs embedded) into Sprague Dawley albino rat intraperitonally for 14 days and measuring various hematological, biochemical and serum enzymatic parameters along with histological examinations. Overall, PMCs showed no significance change in these parameters compared to normal saline administered control which signifies biocompatible nature of the composite. Hence, clean synthesis of FNPs embedded biocompatible amino functional magnetic composite has been achieved which holds potential in number of applications like drug loading, enzyme immobilizations, targeted therapy, etc.

Effect of honeycomb-patterned structure on electrical and magnetic behaviors of poly(@?-caprolactone)/capped magnetic nanoparticle composite films

Kim, J.K.,Basavaraja, C.,Umashankar, M.,Huh, D.S. IPC Science and Technology Press 2016 Polymer Vol.87 No.-

Novel biocompatible poly(@?-caprolactone) (PCL) was synthesized via in situ ring-opening polymerization of @?-caprolactone under different concentrations (10, 20, and 30 wt%) of capped magnetic nanoparticles (CMPs). The prepared PCL/CMP composites were characterized using Fourier transform infrared, UV-vis spectra, and X-ray photoelectron spectroscopy to demonstrate the interaction between PCL and CMP. X-ray diffraction patterns, scanning electron microscopy with energy dispersive X-ray spectroscopy, and thermogravimetric analysis were used to understand the structural nature and thermal stability of the polymer composites. Honeycomb-patterned thin films were fabricated by casting the composite solutions under humid conditions. The I-V characteristics and magnetic behavior of the honeycomb-patterned films were observed and compared with those of the flat thin composite films. The honeycomb-patterned PCL/CMP composite films revealed higher conductivity than the flat films and showed a hysteresis loop in the magnetization plotted against the applied magnetic field for magnetic behavior.

Comparative study on the high frequency performances of the easy-plane FeNi@SiO2 powder soft magnetic composite

Wang Guowu,Zhang Junming,Zheng Zuying,Qiao Liang,Wang Tao,Li Fashen 한국물리학회 2022 Current Applied Physics Vol.41 No.-

In this work, an easy-plane FeNi@SiO2 powder soft magnetic composite (SMC) was imitated and fabricated and its high frequency magnetic properties were comparatively investigated with a non-easy-plane composite. Due to the planar distribution of easy magnetization axes, the easy-plane composite exhibits a constant permeability of 38 up to 100 MHz. Moreover, the easy-plane SMC exhibits a lower core loss at higher frequencies. Loss separated results show that the hysteresis loss plays a dominant loss component in the composite, rather than dominant excess loss in the non-easy-plane powder composite. These results indicate that, compared with non-easy-plane powder composite, the easy-plane powder composites exhibit comprehensive advantages of higher permeability, wider effective operating frequencies and lower loss, which suggest that the use of easy-plane ferromagnetic powder is a promising and efficient measure to develop a new generation of soft magnetic composites for higher frequency application.

고에너지효율 연자성 복합 분말 소재의 연구개발 동향

김휘준(HwiJun Kim) 한국자기학회 2011 韓國磁氣學會誌 Vol.21 No.2

The use of soft magnetic materials have been increasing in the various industrial fields according to the increasing demand for high performance, automatic, miniaturing equipments in the recent our life. In this study, we investigated the effect of factors on the core loss and magnetic properties of electrical steel and soft magnetic composites. Furthermore, we reviewed the major efforts to reduce the core loss and improve the soft magnetic properties in the two main soft magnetic materials. Domain purification which results from reduced density of defects in cleaner electrical steels is combined with large grains to reduce hysteresis loss. The reduced thickness and the high electrical conductivity reduce the eddy current component of loss. Furthermore, the coating applied to the surface of electrical steel and texture control lead to improve high permeability and low core loss. There is an increasing interest in soft magnetic composite materials because of the demand for miniaturization of cores for power electronic applications. The SMC materials have a broad range of potential applications due to the possibility of true 3-D electromagnetic design and higher frequency operation. Grain size, sintering temperature, and the degree of porosity need to be carefully controlled in order to optimize structure-sensitive properties such as maximum permeability and low coercive force. The insulating coating on the powder particles in SMCs eliminates particle-toparticle eddy current paths hence minimizing eddy current losses, but it reduces the permeability and to a small extent the saturation magnetization. The combination of new chemical composition with optimum powder manufacturing processes will be able to result in improving the magnetic properties in soft magnetic composite materials, too.

PMN-PZT/Ni 자기-전기 복합체에서 단결정 압전 모드에 따른 자기장 감도 특성

박소정 ( Sojeong Park ),( Mahesh Peddigari ),류정호 ( Jungho Ryu ) 한국센서학회 2020 센서학회지 Vol.29 No.1

Magnetoelectric (ME) composites were designed using the PMN-PZT single crystal and Ni foils; the properties and magnetic-field sensitivities of ME composites with different piezoelectric vibration modes (i.e., 31, 32, and 36 modes that depend on the crystal orientation of the single crystal) were compared. In the off-resonance condition, the ME coupling properties of the ME composites with the 32 and 36 piezoelectric vibration modes were better than those of the ME composites with the 31 piezoelectric vibration mode. However, in the resonance condition, the ME coupling properties of the ME composites were almost similar, irrespective of the piezoelectric vibration mode. Additionally, in the off-resonance condition (at 1 kHz), the magnetic-field sensitivity of the ME composites with the 36 piezoelectric vibration mode was up to 2 nT and those of the ME composites with the 31 and 32 piezoelectric vibration modes were up to 5 nT. These magnetic-field sensitivities are similar to those offered by conventional high-sensitivity magnetic-field sensors; the potential of the proposed sensor to replace costly and bulky high-sensitivity magnetic field sensors is significant.

FeCo 자성 금속 중공형 섬유 고분자 복합재의 전자파 차폐 특성 연구

최재령 ( Jae Ryung Choi ),정병문 ( Byung Mun Jung ),최우혁 ( U Hyeok Choi ),조승찬 ( Seung Chan Cho ),박가현 ( Ka Hyun Park ),김원정 ( Won Jung Kim ),이상관 ( Sang Kwan Lee ),이상복 ( Sang Bok Lee ) 한국복합재료학회 2015 Composites research Vol.28 No.6

무전해 도금을 통해 제조한 FeCo 자성 금속 중공형 섬유와 EPDM 고분자를 이용하여 전자파 차폐 복합재를 제작하였다. 열처리 공정을 통하여 섬유의 종횡비를 제어하였으며 중공형 구조로 섬유를 제조한 후, 이를 EPDM수지에 첨가하여 복합재를 제조하였다. 자성 금속 중공형 섬유의 종횡비가 클수록 낮은 표면 저항 특성과 우수한 전자파 차폐 성능을 나타내었다. 약 100 μm 길이의 자성 금속 중공형 섬유를 이용한 두께 150 μm 전자파 차폐 복합재의 경우 밀도 1.18 g/cm3, 약 30 ohm/sq의 표면 저항, 그리고 30 dB의 전자파 차폐 성능을 나타내었다. 이는 종횡비가 큰 섬유에 의한 퍼콜레이션 임계치 이상의 전도성 네트워크 형성과 더불어, 낮은 표면 저항에 기인한 임피던스 차이에 의한 반사 손실 증가, 흡수 손실, 그리고 다중 내부 반사 손실에 의하여 우수한 전자파 차폐 성능을 나타내는 것으로 판단된다. Electromagnetic interference shielding composite with low density (1.18 g/cm3) was fabricated using electroless plated FeCo magnetic metal hollow fibers and ethylene propylene diene monomer (EPDM) polymer. Aspect ratio of the fibers were controlled and their hollow structure was obtained by heat treatment process. The FeCo hollow fibers were then mixed with EPDM to manufacture the composite. The higher aspect ratio of the magnetic metal hollow fibers resulted in high electromagnetic interference shielding effectiveness (30 dB) of the composite due to its low sheet resistance (30 ohm/sq). The enhanced electromagnetic interference shielding effectiveness was mainly attributed to the formation of conducting network over the percolation threshold by high aspect ratio of fibers as well as an increase of the reflection loss by impedance mismatch owing to low sheet resistance, absorption loss, and multiple internal reflections loss.