Journal of Powder Materials

[Korean]
Trend in Research and Development Related to Sm-Fe-N Bonded Magnets: Jung-Goo Lee, Hun Kwak, Chul-Jin Choi, Joon-Chul Yun, Jai-Sung Lee; J Korean Powder Metall Inst. 2009;16(1):1-8.; DOI: https://doi.org/10.4150/KPMI.2009.16.1.001

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Advanced Magnetic Actuation: Harnessing the Dynamics of Sm2Fe17–xCuxN3 Composites
Kangmo Koo, Young-Tae Kwon, Ji Young Park, Yong-Ho Choa
ACS Applied Materials & Interfaces.2024; 16(9): 11872. CrossRef

[English]
The Formation and Crystallization of Amorphous Ti₅₀Cu₅₀Ni₂₀Al₁₀ Powder Prepared by High-Energy Ball Milling: Nguyen Hoang Viet, Jin-Chun Kim, Ji-Soon Kim, Young-Soon Kwon; J Korean Powder Metall Inst. 2009;16(1):9-15.; DOI: https://doi.org/10.4150/KPMI.2009.16.1.009

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Amorphization and crystallization behaviors of Ti_50Cu_50Ni_20Al_10 powders during high-energy ball milling and subsequent heat treatment were studied. Full amorphization obtained after milling for 30 h was confirmed by X-ray diffraction and transmission electron microscope. The morphology of powders prepared using different milling times was observed by field-emission scanning electron microscope. The powders developed a fine, layered, homogeneous structure with prolonged milling. The crystallization behavior showed that the glass transition, T_g, onset crystallization, T_x, and super cooled liquid range DeltaT=T_x-T_g were 691,771 and 80 K, respectively. The isothermal transformation kinetics was analyzed by the John-Mehn-Avrami equation. The Avrami exponent was close to 2.5, which corresponds to the transformation process with a diffusion-controlled type at nearly constant nucleation rate. The activation energy of crystallization for the alloy in the isothermal annealing process calculated using an Arrhenius plot was 345 kJ/mol.

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Mechanical Properties of Bulk Amorphous Ti50Cu20Ni20Al10Fabricated by High-energy Ball Milling and Spark-plasma Sintering
H.V. Nguyen, J.C. Kim, J.S. Kim, Y.J. Kwon, Y.S. Kwon
Journal of Korean Powder Metallurgy Institute.2009; 16(5): 358. CrossRef

[Korean]
Mechanical Properties and Fabrication of Nanostructured ReSi_1.75 by High Frequency Induction Heated Combustion Synthesis: Byung-Ryang Kim, Su-Chul Kim, In-Jin Shon; J Korean Powder Metall Inst. 2009;16(1):16-21.; DOI: https://doi.org/10.4150/KPMI.2009.16.1.016

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Abstract PDF: Nanostructured ReSi_1.75 was synthesized to have high density via rapid and cost effective process named as high-frequency induction heated combustion synthesis(HFIHCS) method. For the process, mechanically activated Re-Si powder was used, which had been prepared by mechanical ball milling of Re and Si powders with mixing ratio of 1:1.75. Both combustion synthesis and densification were accomplished simultaneously by applying electric current and mechanical pressure of 80 MPa during the process. The average grain size, hardness, and fracture toughness of the compound were 210 nm, 1085 kg/mm2 and 4 MPacdotm1/2, respectively. The experimental results show that HFIHCS is a promising process for synthesis of nanostructured ReSi_1.75 which has a potential for both high temperature and thermo-electric applications.

[Korean]
The Formation of Hybridized Porous Structure of Al Alloy by Alkali Surface Modification: Young-Ik Seo, Young-Moon Kim, Young-Jung Lee, Dae-Gun Kim, Kyu-Hwan Lee, Young-Do Kim; J Korean Powder Metall Inst. 2009;16(1):22-27.; DOI: https://doi.org/10.4150/KPMI.2009.16.1.022

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To improve the filtration efficiency of porous materials used in filters, an extensive specific surface area is required to serve as a site for adsorption of impurities. In this paper, a method for creating a hybridized porous alloy using a powder metallurgical technique to build macropores in an Al-4 wt.% Cu alloy and subsequent surface modification for a microporous surface with a considerably increased specific surface area is suggested. The macropore structure was controlled by granulation, compacting pressure, and sintering; the micropore structure was obtained by a surface modification using a dilute NaOH solution. The specific surface area of surface-modified specimen increased about 10 times compare to as-sintered specimen that comprised of the macropore structure. Also, the surface-modified specimens showed a remarkable increase in micropores larger than 10 nm. Such a hybridized porous structure has potential for application in water and air purification filters, as well as membrane pre-treatment and catalysis.

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Development of Vacuum Thin-Film-Forming Mold using Porous Aluminum
Hyung-Sun Kang, Sunghyun Lee
Journal of the Korean Society of Manufacturing Technology Engineers.2020; 29(6): 435. CrossRef
Phosphorus removal from wastewater by ionic exchange using a surface-modified Al alloy filter
Young Ik Seo, Ki Ho Hong, Se Hoon Kim, Duk Chang, Kyu Hwan Lee, Young Do Kim
Journal of Industrial and Engineering Chemistry.2013; 19(3): 744. CrossRef

[Korean]
Getter Properties of Ti_80-XZr₂₀V_X Alloy Powders: Je-Shin Park, Won-Baek Kim, Chang-Youl Soh, Sung-Wook Cho; J Korean Powder Metall Inst. 2009;16(1):28-32.; DOI: https://doi.org/10.4150/KPMI.2009.16.1.028

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Abstract PDF: The activation temperatures and hydrogen sorption rates of Ti_80-XZr_20V_X alloys were evaluated at room temperature. The alloy powders were prepared by arc melting and then hydride-dehydride(HDH) process. The alloy powders were apt to activate by increase of vanadium in Ti-Zr-V alloys. The easy activation was explained in terms of surface oxygen content which decreased with increase of vanadium on Ti-Zr-V alloys.

[English]
Electromagnetic Wave Absorption Properties in Fe-based Nanocrystalline P/M Sheets with Carbon Black and BaTiO₃ Additives: Mi-Rae Kim, Won-Wook Park; J Korean Powder Metall Inst. 2009;16(1):33-36.; DOI: https://doi.org/10.4150/KPMI.2009.16.1.033

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In order to increase the magnetic loss for electromagnetic(EM) wave absorption, the soft magnetic Fe_73Si_16B_7Nb_3Cu_1(at%) alloy strip was used as the basic material in this study. The melt-spun strip was pulverized using an attrition mill, and the pulverized flake-shaped powder was crystallized at 540°C for 1h to obtain the optimum grain size. The Fe-based powder was mixed with 2 wt% BaTiO_3, 0.3sim0.6 wt% carbon black, and polymer-based binders for the improvement of electromagnetic wave absorption properties. The mixture powders were tape-cast and dried to form the absorption sheets. After drying at 100°C for 1h, the sheets of 0.5 mm in thickness were made by rolling at 60°C, and cut into toroidal shape to measure the absorption properties of samples. The characteristics including permittivity, permeability and power loss were measured using a Network Analyzer(N5230A). Consequently, the properties of electromagnetic wave absorber were improved with the addition of both BaTiO_3 and carbon black powder, which was caused by the increased dielectric loss of the additive powders.

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Synthesis of Fe(Ni) nanoparticles by calcination and hydrogen reduction of metal nitrate powders
Sung-Tag Oh, Min-Hee Joo, Yong-Ho Choa, Ki Hyeon Kim, Sang-Kwan Lee
Physica Scripta.2010; T139: 014050. CrossRef
Synthesis and Properties of Fe-Ni Nano-sized Powders using Metal Nitrates
Min-Hee Joo, Sung-Tag Oh
Journal of Korean Powder Metallurgy Institute.2009; 16(3): 191. CrossRef

[Korean]
Feasibility Test for Mechanical Property Characterization of BaTiO₃ Ceramics for MLCC Application Using Nanoindentation: Sung-Soo Ryu, Seong-Won Kim, Hyeong-Jun Kim, Hyung-Tae Kim; J Korean Powder Metall Inst. 2009;16(1):37-42.; DOI: https://doi.org/10.4150/KPMI.2009.16.1.037

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Abstract PDF: In this study, the feasible test for the mechanical property characterization of BaTiO_3 ceramics and multi-layer ceramic capacitor(MLCC) was performed with nanoindentation technique. In case of BaTiO_3 ceramics, hardness and elastic modulus are dependent on the densification of specimen showing the highest hardness and elastic modulus values of 12.3 GPa and 155 GPa, respectively at 1260°C. In case of MLCC chip, hardness of dielectric layer was lower than that of margin region. The nanoindentation method could be useful tool for the measurement of mechanical property within BaTiO_3 dielectric layer of very thin thickness in high capacitance MLCC.

[English]
Synthesis of Titanium Carbide Nano Particles by the Mechano Chemical Process: In-Shup Ahn, Dong-Kyu Park, Yong-Hee Lee; J Korean Powder Metall Inst. 2009;16(1):43-49.; DOI: https://doi.org/10.4150/KPMI.2009.16.1.043

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Titanium carbides are widely used for cutting tools and grinding wheels, because of their superior physical properties such as high melting temperature, high hardness, high wear resistance, good thermal conductivity and excellent thermal shock resistance. The common synthesizing method for the titanium carbide powders is carbo-thermal reduction from the mixtures of titanium oxide(TiO_2) and carbon black. The purpose of the present research is to fabricate nano TiC powders using titanium salt and titanium hydride by the mechanochemical process(MCP). The initial elements used in this experiment are liquid TiCl_4(99.9%), TiH_2(99.9%) and active carbon(<32µm, 99.9%). Mg powders were added to the TiCl_4 solution in order to induce the reaction with Cl-. The weight ratios of the carbon and Mg powders were theoretically calculated. The TiC and MgCl_2 powders were milled in the planetary milling jar for 10 hours. The 40 nm TiC powders were fabricated by wet milling for 4 hours from the TiCl_4+C+Mg solution, and 300 nm TiC particles were obtained by using titanium hydride.

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Quantitative Study on the Refinement Behaviors of TiC Powders Produced by Mechanical Milling Under Different Impact Energy
Sung-Mo Hong, Eun-Kwang Park, Kyeong-Yeol Kim, Jin-Ju Park, Min-Ku Lee, Chang-Kyu Rhee, Jin-Kyu Lee, Young-Soon Kwon
Journal of Korean Powder Metallurgy Institute.2012; 19(1): 32. CrossRef

[Korean]
Analysis of Densification Behavior of Magnesium Powders in Extrusion using the Critical Relative Density Model: Seung-Chae Yoon, Hong-Jun Chae, Taek-Soo Kim, Hyoung-Seop Kim; J Korean Powder Metall Inst. 2009;16(1):50-55.; DOI: https://doi.org/10.4150/KPMI.2009.16.1.050

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Abstract PDF: Numerical simulations of the powder extrusion need an appropriate pressure-dependent constitutive model for densification modeling of the magnesium powders. The present research investigated the effect of representative powder yield function of the critical relative density model. We could obtain reasonable physical properties of pure magnesium powders using cold isostatic pressing. The proposed densification model was implemented into the finite element code. The finite element analysis was applied to simulation of powder extrusion of pure magnesium powder in order to investigate the densification and processing load at room temperature.

[Korean]
Microstructural Characteristics of Thermally Sprayed WC-Co Coatings: Hee-Soo Kang, Kyeong-Ho Baik; J Korean Powder Metall Inst. 2009;16(1):56-62.; DOI: https://doi.org/10.4150/KPMI.2009.16.1.056

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Abstract PDF: The degree of WC decomposition and hardness of thermally sprayed WC-Co coatings are important factors determining the wear resistance of the coatings. In order to minimize the degree of decomposition and to increase hardness, the effects of processing parameters of high velocity oxyfuel(HVOF) spraying on various characteristics of nanostructured WC-12Co coating have been evaluated by an experimental design method. The HVOF sprayed WC-12Co coatings consisted of various carbide phases including WC, W_2C and W_3Co_3C, with a much reduced carbon content. The degree of WC decomposition and decarburization was affected by changing barrel length and spray distance. The hardness of WC-Co coatings was strongly related to droplet temperature at substrate, and increased with increasing fuel addition and/or decreasing spray distance. The effective control of processing parameters was discussed in detail for manufacturing a high performance WC-Co coating.

[Korean]
Effect of Spark Plasma Sintering on the Materials Properties of Water Atomized Al-Zn-Mg Alloy: Sun-Mi Kim, Taek-Soo Kim, Young-Do Kim, Jeong-Gon Kim; J Korean Powder Metall Inst. 2009;16(1):63-67.; DOI: https://doi.org/10.4150/KPMI.2009.16.1.063

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In order to investigate the effect of rapid solidification on the microstructure and the mechanical properties of Al-Zn-Mg system alloys, water atomization was carried out, since the water atomization beared the highest solidification rate among the atomization processes. The as atomized alloy powders consisted of fine grains less than 4 µm in diameter, and the second particles were not detected on XRD. The microstructure as solidified was maintained even after the spark plasma sintering at the heating rate of 50 K/min. On the other hand, lower rate of 20 K/min induced a formation of MgZn_2 particles, resulting in strengthening of the matrix. The density was almost constant at the temperature above 698K. The sintering temperature above 698K had no effect on the strength of the sintered materials.

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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

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