Journal of Powder Materials

Application of Refractory Metal Powders to Military Material Fields: Young-Moo Kim, Eun-Pyo Kim, Seong Lee, Joon-Woong Noh; J Korean Powder Metall Inst. 2007;14(4):221-229.; DOI: https://doi.org/10.4150/KPMI.2007.14.4.221

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Synthesis and Nucleation Behavior of MoO₃ Nano Particles with Concentration of Precursors
Seyoung Lee, Namhun Kwon, Jaeseok Roh, Kun-Jae Lee
Journal of Korean Powder Metallurgy Institute.2020; 27(5): 394. CrossRef
Fabrication of Ultra Fine Grained Molybdenum and Mechanical Properties
Se-Hoon Kim, Young-Ik Seo, Dae-Gun Kim, Myung-Jin Suk, Young-Do Kim
Journal of Korean Powder Metallurgy Institute.2010; 17(3): 235. CrossRef

The Densification Properties of Distaloy AE-TiC Cermet by Spark Plasma Sintering: Ho-Jung Cho, In-Shup Ahn, Young-Hee Lee, Dong-Kyu Park; J Korean Powder Metall Inst. 2007;14(4):230-237.; DOI: https://doi.org/10.4150/KPMI.2007.14.4.230

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Abstract PDF: The fabrication of Fe alloy-40 wt.%TiC composite materials using spark plasma sintering process after ball-milling was studied. Raw powders to fabricate Fe alloy-TiC composite were Fe alloy, TiH_2 and activated carbon. Fe alloy powder was Distaloy AE (4%Ni-1%Cu-0.5%Mo-0.01%C-bal.%Fe) made by Hoeganes company with better toughness and lower melting point. These powders were ball-milled in horizontal attrition ball mill at a ball-to-powder weight ratio of 30 : 1. After that, these mixture powders were sintered by using spark plasma sintering apparatus for 5 min at 1200-1275°C in vacuum atmosphere under 10-3 torr. DistaloyAE-40 wt.%TiC composite was directly synthesized by dehydrogenation and carburization reaction during sintering process. The phase transformation of as-milled powders and sintered materials was confirmed using X-ray diffraction (XRD) and transmission electron microscope (TEM). The density and harness materials was measured in order to confirm the densification behavior. In case of DistaloyAE-40 wt.%TiC composite retained for 5 min at 1275°C, it has the relative density of about 96% through the influence of rapid densification and fine TiC particle reinforced Fe-based composites materials.

Self-repairing Technology by Electrophoresis of Ni Nano-Particles for Heat Exchanger Tubes: Gyoung-Ja Lee, Min-Ku Lee, Chang-Kyu Rhee; J Korean Powder Metall Inst. 2007;14(4):238-244.; DOI: https://doi.org/10.4150/KPMI.2007.14.4.238

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The electrophoretic deposition process of Ni nano-particles in organic suspension was employed for self-repairing of heat exchanger tubes. For this purpose, Ni nano-particles prepared by levitational gas condensation method were dispersed into the solution of ethanol with the addition of dispersant Hypermer KD2. For electrophoretic deposition of Ni nano-particles on the Ni alloy specimen, constant electric fields of 20 and 100 V cm-1 were applied to the specimen in Ni-dispersed solution. It was found that as electrophoretic deposition proceeds, the size of the pit or crack remarkably decreased due to the agglomeration of Ni nano-particles at the pit or crack. This strongly suggests that the electrophoretic mobility of the charged particles is larger for the damaged part with a higher current value rather than outer surfaces with a lower current value.

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Electrophoretic deposition of Ni nanoparticles from suspension on to a Ni plate
Keun-Yong Park, Young Rang Uhm, Kwang Jae Son, Deok-Yong Park
Research on Chemical Intermediates.2015; 41(9): 6721. CrossRef

Mechanical Properties and Fabrication of Nanostructured 2MoSi₂-SiC by Pulsed Current Activated Combustion Synthesis: In-Jin Shon, Dong-Ki Kim, In-Kyoon Jeong, Jung-Mann Doh, Jin-Kook Yoon, In-Yong Ko; J Korean Powder Metall Inst. 2007;14(4):245-250.; DOI: https://doi.org/10.4150/KPMI.2007.14.4.245

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Abstract PDF: Dense nanostructured 2MoSi_2-SiC composites were synthesized by the pulsed current activated combustion synthesis (PCACS) method within 3 minutes in one step from mechanically activated powders of Mo_2C and 5Si. Simultaneous combustion synthesis and densification were accomplished under the combined effects of a pulsed current and mechanical pressure. Highly dense 2MoSi_2-SiC with relative density of up to 96% was produced under simultaneous application of a 60 MPa pressure and the pulsed current. The average grain size of MoSi_2 and SiC were about 120 nm and 90 nm, respectively. The hardness and fracture toughness values obtained were 1350 kg/mm2 and 4 MPacdotm1/2, respectively.

Extrusion Behavior of Gas Atomized Mg Alloy Powders: Hong-Jun Chae, Young-Do Kim, Jin-Kyu Lee, Jeong-Gon Kim, Taek-Soo Kim; J Korean Powder Metall Inst. 2007;14(4):251-255.; DOI: https://doi.org/10.4150/KPMI.2007.14.4.251

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This work is to report not only the effect of rapid solidification of MgZn_4.3Y_0.7 alloys on the micro-structure, but also the extrusion behavior on the materials properties. The average grain size of the atomized powders was about 3-4µm. The alloy powders of Mg_97Zn_4.3Y_0.7, consisted of I-Phase (Icosahedral, Mg_3Zn_6Y_1) as well as Cubic structured W-Phase (Mg_3Zn_3Y_2), which was finely distributed within alpha-Mg matrix. The oxide layer formed along the Mg surface was about 48 nm in thickness. In order to study the consolidation behavior of Mg alloy powders, extrusion was carried out with the area reduction ratio of 10:1 to 20:1. As the ratio increased, fully deformed and homogeneous microstructure could be obtained, and the mechanical properties such as tensile strength and elongation were simultaneously increased.

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Fabrication and Dynamic Consolidation Behaviors of Rapidly Solidified Mg Alloy Powders
Hong-Jun Chae, Young-Do Kim, Taek-Soo Kim
Journal of Korean Powder Metallurgy Institute.2011; 18(4): 340. CrossRef

Functionalization of Fe₃O₄ Nanoparticles and Improvement of Dispersion Stability for Seperation of Biomolecules: Min-Jung Kim, Guk-Hwan An, Borami Lim, Hee-Taik Kim, Yong-Ho Choa; J Korean Powder Metall Inst. 2007;14(4):256-260.; DOI: https://doi.org/10.4150/KPMI.2007.14.4.256

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Abstract PDF: The surface of magnetite (Fe_3O_4) nanoparticles prepared by coprecipitation method was modified by carboxylic acid group of poly(3-thiophenacetic acid (3TA)) and meso-2,3-dimercaptosuccinic acid (DMSA). Then the lysozyme protein was immobilized on the carboxylic acid group of the modification of the magnetite nanoparticles. The magnetite nanoparticles are spherical and the particle size is approximately 10 nm. We measured quantitative dispersion state by dispersion stability analyzer for each Fe_3O_4 nanoparticles with and without surface modification. The concentration of lysozyme on the modified magnetite nanoparticles was also investigated by a UV-Vis spectrometer and compared to that of magnetite nanoparticles without surface modification. The functionalized magnetite particles had higher enzymatic capacity and dispersion stability than non-functionalized magnetite nanoparticles.

Study of Electromagnetic Wave Absorption Properties with Particle Size in Soft Magnetic Alloy Powder: S.H. Hong, K.Y. Sohn, W.W. Park, J.M. Nam, B.G. Moon, Y.S. Song; J Korean Powder Metall Inst. 2007;14(4):261-264.; 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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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: S.J. Woo, E.K. Cho, H.J. Cho, J.J. Lee, K.Y. Sohn, W.W. Park; J Korean Powder Metall Inst. 2007;14(4):265-271.; DOI: https://doi.org/10.4150/KPMI.2007.14.4.265

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Abstract PDF: 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.

Influence of Boron Content on the Thermoelectric Properties of p-type Si_0.8Ge_0.2 Alloy: Sung-Doo Hwang, Woo-Suk Choi, Ik-Min Park, Yong-Ho Park; J Korean Powder Metall Inst. 2007;14(4):272-276.; DOI: https://doi.org/10.4150/KPMI.2007.14.4.272

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Abstract PDF: P-type thermoelectric material Si_0.8Ge_0.2 was sintered by Hot Press process (HP) and the effect of boron (0.25sim2 at%) addition on the thermoelectric properties were reported. To enhance the thermoelectric performances, the Si_0.8Ge_0.2, alloys were fabricated by mechanical alloying (MA) and HP. The carrier of p-type SiGe alloy was controlled by B-doping. The effect of sintering condition and thermoelectric properties were investigated. B-doped SiGe alloys exhibited positive seebeck coefficient. The electrical conductivity and thermal conductivity were increased at the small amount of boron content (0.25sim0.5 at%). However, they were decreased over 0.5 at% boron content. As a result, the small addition of boron improved the Z value. The Z value of 0.5 at% B doped Si_0.8Ge_0.2 B alloy was 0.9times10-4/K, the highest value among the prepared alloys.

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