• Title/Summary/Keyword: a soft magnetic composite powders

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Fabrication and Structural Observation of a Soft Magnetic Composite Powders by Mechanical Alloying (기계적합금화법에 의한 연자성 복합분말의 제조 및 구조관찰)

  • Lee, Chung-Hyo
    • Korean Journal of Materials Research
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    • v.29 no.4
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    • pp.252-257
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    • 2019
  • Fabrication of soft magnetic composite powders for the $Fe_2O_3-Ca$ system by mechanical alloying(MA) has been investigated at room temperature. It is found that soft magnetic composite powders in which CaO is dispersed in ${\alpha}-Fe$ matrix are obtained by MA of $Fe_2O_3$ with Ca for 5 hours. Changes in magnetization and coercivity also reflect the details of the solidstate reduction process of hematite by pure metal of Ca during MA. The saturation magnetization of MA powders increases with increasing MA time and reaches a maximum value of 65 emu/g after 7 hours of MA. The average grain size of ${\alpha}-Fe$ in MA powders, estimated by diffraction line-width, gradually decreases with increasing MA time and reaches 52 nm after 5 hours of MA. It can also be seen that the coercivity of the 5-hour MA sample is fairly high at 190 Oe, suggesting that the grain refinement of already-produced ${\alpha}-Fe$ tends to clearly occur during MA.

Synthesis and Characterization of Soft Magnetic Composite Powders in Fe2O3-Zn System by Mechanical Alloying (기계적 합금화법에 의한 Fe2O3-Zn계 연자성 복합분말의 제조 및 특성평가)

  • Lee, Chung-Hyo
    • Korean Journal of Materials Research
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    • v.30 no.2
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    • pp.74-80
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    • 2020
  • Synthesis of composite powders for the Fe2O3-Zn system by mechanical alloying (MA) has been investigated at room temperature. Optimal milling and heat treatment conditions to obtain soft magnetic composite with fine microstructure were investigated by X-ray diffraction, differential scanning calorimetry (DSC) and vibrating sample magnetometer (VSM) measurement. It is found that α-Fe/ZnO composite powders in which ZnO is dispersed in α-Fe matrix can be obtained by MA of Fe2O3 with Zn for 4 hours. The change in magnetization and coercivity also reflects the details of the solid-state reduction process of hematite by pure metal of Zn during MA. Densification of the MA powders was performed in a spark plasma sintering (SPS) machine at 900 ~ 1,000 ℃ under 60 MPa. Shrinkage change after SPS of sample MA'ed for 5 hrs was significant above 300 ℃ and gradually increased with increasing temperature up to 800 ℃. X-ray diffraction results show that the average grain size of α-Fe in the α-Fe/ZnO composite sintered at 900 ℃ is in the range of 110 nm.

Synthesis and characterization of soft magnetic composite in Fe2O3-Mg system by mechanical alloying (기계적합금화에 의한 Fe2O3-Mg계 연자성 콤포지트의 합성 및 평가)

  • Lee, Chung-Hyo
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.25 no.6
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    • pp.245-251
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    • 2015
  • We have applied mechanical alloying (MA) to produce soft magnetic composite material using a mixture of elemental $Fe_2O_3$-Mg powders. An optimal milling and heat treatment conditions to obtain soft magnetic ${\alpha}$-Fe/MgO composite with fine microstructure were investigated by X-ray diffraction, differential scanning calorimetry (DSC) and vibrating sample magnetometer (VSM) measurement. It is found that ${\alpha}$-Fe/MgO composite powders in which MgO is dispersed in ${\alpha}$-Fe matrix are obtained by MA of $Fe_2O_3$ with Mg for 30 min. The saturation magnetization of ball-milled powders increases with increasing milling time and reaches to a maximum value of 69.5 emu/g after 5 h MA. The magnetic hardening due to the reduction of the ${\alpha}$-Fe grain size by MA was also observed. Densification of the MA powders was performed in a spark plasma sintering (SPS) machine at $800{\sim}1000^{\circ}C$ under 60 MPa. X-ray diffraction result shows that the average grain size of ${\alpha}$-Fe in ${\alpha}$-Fe/MgO nanocomposite sintered at $800^{\circ}C$ is in the range of 110 nm.

The Variation of Packing Density According to Powder Size Distribution and Epoxy Resin in Soft Magnetic Composite (연자성 복합체에서 파우더 크기 분포와 Epoxy Resin에 따른 Packing Density 변화)

  • Lee, Chang Hyun;Oh, Sea Moon;Shin, Hyo Soon;Yeo, Dong Hun;Kim, Jin Ho
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.30 no.12
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    • pp.782-787
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    • 2017
  • There is growing interest in power inductors in which metal soft magnetic powder and epoxy resin are combined. In this field, the process technology for increasing the packing density of magnetic particles in an injection molding process is very important. However, little research has been reported in this regard. In order to improve the packing density, we investigated and compared the sedimentation heights of pastes for three types of soft magnetic alloy powders as a function of the mixing ratios and the type of resin used. Experimental results showed that the packing density was the highest (71.74%) when the mixing ratio was 80 : 16 : 4 (Sendust : Fe-S : CIP) according to the particle size using an SE-4125 resin. In addition, the packing density was found to be inversely related to the layer separation distance. As a result, it was confirmed that the dispersion of solid particles in the paste was important for curing; however, the duration of the curing process can greatly affect the packing density of the final composite.

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

  • Hong, Won Sik;Kim, Sang Hyun;Park, Ji-Yeon;Oh, Chulmin;Lee, Woo Sung;Kim, Seung Gyeom;Han, Sang Jo;Shim, Geum Taek;Kim, Hwi-Jun
    • Journal of the Microelectronics and Packaging Society
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    • v.23 no.2
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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.

The Effect of Silane and Dispersant on the Packing in the Composite of Epoxy and Soft Magnetic Metal Powder (실란 및 분산제가 Epoxy와 연자성 금속 파우더 복합체의 Packing에 미치는 영향)

  • Lee, Chang Hyun;Shin, Hyo Soon;Yeo, Dong Hun;Nahm, Sahn
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.30 no.12
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    • pp.751-756
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    • 2017
  • A molding-type power inductor is an inductor that uses a hybrid material that is prepared by mixing a ferrite metal powder coated with an insulating layer and an epoxy resin, which is injected into a coil-embedded mold and heated and cured. The fabrication of molding-type inductors requires various techniques such as for coil formation and insertion, improving the magnetic properties of soft magnetic metal powder, coating an insulating film on the magnetic powder surface, and increasing the packing density by well dispersing the powder in the epoxy resin. Among these aspects, researches on additives that can disperse the metal soft magnetic powder having the greatest performance in the epoxy resin with high charge have not been reported yet. In this study, we investigated the effect of silanes, KBM-303 and KBM-403, and a commercial dispersant on the dispersion of metal soft magnetic powders in epoxy resin. The sedimentation height and viscosity were measured, and it was confirmed that the silane KBM-303 was suitable for dispersion. For this silane, the packing density was as high as about 72.49%. Moreover, when 1.2 wt% of dispersant BYK-103 was added, the packing density was about 80.5%.

Electromagnetic Wave Absorbing Properties of FeSiCr and Fe50Ni Flaky Powder-Polymer Composite Sheet (FeSiCr에 Fe50Ni가 첨가된 폴리머 복합 시트의 전자파 흡수 특성)

  • Lee, Seok-Moon;Kim, Sang-Mun
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.27 no.7
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    • pp.462-467
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    • 2014
  • In this paper, we studied the magnetic composite sheets for electromagnetic wave noise absorber of quasi-microwave band by using soft magnetic FeSiCr and Fe50Ni flakes with the thickness of about $1{\mu}m$ and polymer. The magnetic hysteresis curve including saturation magnetization and residual magnetization and the complex permeability characteristics of the composite sheets were investigated to clarify the mixing effect on electromagnetic wave absorption properties. The saturation magnetization was decreased about 10% while the residual magnetization was increased about 15% and the real parts of complex permeability at below 500 MHz were increased 0.6~4 while those values at above 500 MHz were decreased 0.4~2.5 according to the change of contents of FeSiCr and Fe50Ni powders. As a result, the reflection loss can be moved to the lower frequency from 2~3 GHz to 1~1.5 GHz as the contents of Fe50Ni flaky powder into FeSiCr flaky powder was increased up to 50%.

Optimization of Slurry Preparation Process for Soft Magnetic Green Sheet (연자성 복합체 후막용 슬러리 제조공정의 최적화)

  • Oh, Sea Moon;Lee, Chang Hyun;Shin, Hyo Soon;Yeo, Dong Hun;Kim, Jin Ho
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.28 no.12
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    • pp.792-796
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    • 2015
  • With high integration of electronic components, power inductors are also miniaturized. Recently, thick film processes for small size power inductors were developed and commercialized. However, the thick film process to prepare soft magnetic green sheets was not reported enough. In this study, we used Fe-Si magnetic and CIP (carbonyl iron powders) as starting materials to lead to a bimodal particle size distribution in the sheet. We proposed a newly developed 'Modified slurry preparation process' to get well dispersed condition even at high solid contents. Using the new process, it was possible to prepare a well dispersed slurry over 70 vol% of solid. BYK-103 was better than BYK-111 as dispersant in this slurry and the optimum amount was 0.6 wt%. The optimized slurry was formed into a sheet by tape casting process and then the sheet was laminated. We conformed that small size powder, large size powder, and epoxy resin were well dispersed in the green sheet.