- Electromagnetic Wave Absorption Behavior of a Fe-based Nanocrystalline Alloy mixed with a Ferrite Powder
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S.K. Koo, M.H. Lee, B.G. Moon, Y.S. Song, K.Y. Sohn, W.W. Park
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J Korean Powder Metall Inst. 2008;15(4):292-296.
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DOI: https://doi.org/10.4150/KPMI.2008.15.4.292
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- The electromagnetic (EM) wave absorption properties of the Fe_73Si_16B_7Nb_3Cu_1 nanocrystalline powder mixed with 5 to 20 vol% of Ni-Zn ferrites has been investigated in a frequency range from 100MHz to 10GHz. Amorphous ribbons prepared by a planar flow casting process were pulverized and milled after annealing at 425 for 1 hour. The powder was mixed with a ferrite powder at various volume ratios to tape-cast into a 1.0mm thick sheet. Results showed that the EM wave absorption sheet with Ni-Zn ferrite powder reduced complex permittivity due to low dielectric constant of ferrite compared with nanocrystalline powder, while that with 5 vol% of ferrite showed relatively higher imaginary part of permeability. The sheet mixed with 5 vol% ferrite powder showed the best electromagnetic wave absorption properties at high frequency ranges, which resulted from the increased imaginary part of permeability due to reduced eddy current.
- Effect of Annealing Temperature on the Electromagnetic Wave Absorbing Properties of Nanocrystalline Soft-magnetic Alloy Powder
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S.H. Hong, K.Y. Sohn, W.W. Park, B.G. Moon, Y.S. Song
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J Korean Powder Metall Inst. 2008;15(1):18-22.
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DOI: https://doi.org/10.4150/KPMI.2008.15.1.018
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- The electromagnetic (EM) wave absorption properties with a variation of crystallization annealing temperature have been investigated in a sheet-type absorber using the Fe_73Si_16B_7Nb_3Cu_1 alloy powder. With increasing the annealing temperature the complex permeability (µ_r), permittivity (varepsilon_r) and power absorption changed. The EM wave absorber shows the maximum permeability and permittivity after the annealing at 610°C for 1 hour, and its calculated power absorption is above 80% of input power in the frequency range over 1.5 GHz.
- Effect of the Surface Oxidation on the Electromagnetic Wave Absorption Behavior of a Fe-based Nanocrystalline Alloy
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S.K. Koo, S.J. Woo, B.G. Moon, Y.S. Song, W.W. Park, K.Y. Sohn
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J Korean Powder Metall Inst. 2007;14(5):303-308.
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DOI: https://doi.org/10.4150/KPMI.2007.14.5.303
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- The oxidation of Fe_73Si_16B_7Nb_3Cu_1 nanocrystalline powder has been conducted to investigate its influence on the electromagnetic wave absorption characteristics of the soft magnetic material. Oxidation occurred primarily on the surface of nanocrystals. Oxidation reduced the real part of complex permeability due to the reduction of the relative volume of the powder, which otherwise contributes to the permeability. Oxidation reduced the absorption efficiency of the sheet at frequencies over 1GHz, indicating that the relative contribution of skin depth increments to the absorption was not significant. The pulverization and milling process lowered the optimum crystallization temperature of the material by 40sim50°C because of the internal energy accumulated during the fragmentation and powder thinning processes.
- Study of Electromagnetic Wave Absorption Properties with Particle Size in Soft Magnetic Alloy Powder
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S.H. Hong, K.Y. Sohn, W.W. Park, J.M. Nam, B.G. Moon, Y.S. Song
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J Korean Powder Metall Inst. 2007;14(4):261-264.
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DOI: https://doi.org/10.4150/KPMI.2007.14.4.261
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- The electromagnetic wave (EM) absorption properties of various particle size have been investigated in a sheet-type absorber using the Fe_73Si_16B_7Nb_3Cu_1 alloy powder. With decreasing the average particle size, the complex permeability (µ_r) and permittivity (varepsilon_r) increased and the matching frequency is shifted toward lower frequency. The fabricated EM wave absorbers showed permeability 2sim6, permittivity 17sim23 for a -325sim+400 mesh sample, and the calculated power absorption was as high as 80% in the frequency range over 2 GHz.
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Citations
Citations to this article as recorded by  - Influence of Coating Agent and Particle Size on the Soft Magnetic Properties of Fe Based Nano Crystalline Alloy Powder Core
S.J. Jang, Y.J. Choi, S.W. Kim, B.S. Jeon, T.H. Lee, C.B. Song, J. Namkung
Journal of the Korean Magnetics Society.2015; 25(3): 67. CrossRef - Electromagnetic Wave Shielding Effect of Nano-powder Dispersed Epoxy Resin Composite
Jun-Young Han, Chul-Hee Lee, Min-Gyu Choi, Soon-Jik Hong, Joong-Hark Park, Dong-Jin Lee
journal of Korean Powder Metallurgy Institute.2015; 22(4): 234. CrossRef - Electromagnetic Wave Absorption Properties of Fe73Si16B7Nb3Cu1-Based Nanocrystalline Soft Magnetic Powder Composite Mixed with Charcoal Powder
Sun-I Kim, Mi-Rae Kim, Keun-Yong Sohn, Won-Wook Park
Journal of Korean Powder Metallurgy Institute.2009; 16(4): 291. CrossRef
- Electromagnetic Wave Absorption Properties of Fe-based Nanocrystalline P/M sheets with Al2O3 additive
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S.J. Woo, E.K. Cho, H.J. Cho, J.J. Lee, K.Y. Sohn, W.W. Park
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J Korean Powder Metall Inst. 2007;14(4):265-271.
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DOI: https://doi.org/10.4150/KPMI.2007.14.4.265
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- Electromagnetic wave absorbing materials have been developed to reduce electromagnetic interference (EMI) for electronic devices in recent years. In this study, Fe-Si-B-Nb-Cu base amorphous strip was pulverized using a jet mill and an attritor and heat-treated to get flake-shaped nanocrystalline powders, and then the powders were mixed, cast and dried with dielectric Al_2O_3 powders and binders. As a result, the addition of Al_2O_3 powders improved the absorbing properties of the sheets noticeably compared with those of the sheets without dielectric materials. The sheet mixed with 2 wt% Al_2O_3 powder showed the best electromagnetic wave absorption, which was caused by the increase of the permittivity and the electric resistance due to the dielectric materials finely dispersed on the Fe-based powder.
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