Journal of Powder Materials

Finite Element Analysis of Densification of Mg Powders during Equal Channel Angular Pressing: Effect of Sheath: Seung-Chae Yoon, Taek-Soo Kim, Hyoung-Seop Kim; J Korean Powder Metall Inst. 2009;16(2):85-90.; DOI: https://doi.org/10.4150/KPMI.2009.16.2.085

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Abstract PDF: Magnesium and its alloys are attractive as light weight structural/functional materials for high performance application in automobile and electronics industries due to their superior physical properties. In order to obtain high quality products manufactured by the magnesium powders, it is important to control and understand the densification behavior of the powders. The effect of the sheath surrounding the magnesium powders on the plastic deformation and densification behavior during equal channel angular pressing was investigated in the study by experimental and the finite element methods. A modified version of Lee-Kim's plastic yield criterion, notably known as the critical relative density model, was applied to simulate the densification behavior of magnesium powders. In addition, a new approach that extracts the mechanical characteristics of both the powder and the matrix was developed. The model was implemented into the finite element method, with which powder compaction under equal channel angular pressing was simulated.

Fabrication of 4.25 Co_0.53Fe_0.47-Al₂O₃ Composite by High Frequency Induction Heated Combustion Synthesis: Na-Ra Park, Hoon NamKung, In-Yong Ko, In-Jin Shon; J Korean Powder Metall Inst. 2009;16(2):91-97.; DOI: https://doi.org/10.4150/KPMI.2009.16.2.091

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Abstract PDF: Nanopowders of Co_3O_4 and FeAl were fabricated by high energy ball milling. Dense 4.25 Co_0.53Fe_0.47-Al_2O_3 composite was simultaneously synthesized and consolidated by high frequency induction heated combustion method within 2 min from mechanically activated powders. Consolidation was accomplished under the combined effects of a induced current and mechanical pressure of 80 MPa.

Preparation of Ultrafine TiCN Powders by Mg-reduction of Metallic Chlorides: Dong-Won Lee, Jin-Chun Kim, Yong-Jin Kim, Byoung-Kee Kim; J Korean Powder Metall Inst. 2009;16(2):98-103.; DOI: https://doi.org/10.4150/KPMI.2009.16.2.098

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The ultrafine titanium carbonitride particles (TiC_0.7N_0.3) below 100nm in mean size were successfully synthesized by Mg-thermal reduction process. The nanostructured sub-stoichiometric titanium carbide (TiC_0.7) particles were produced by the magnesium reduction at 1123K of gaseous TiC_l4+xC_2Cl_4 and the heat treatments in vacuum were performed for five hours to remove residual magnesium and magnesium chloride mixed with TiC_0.7. And final TiC_0.7N_0.3 phase was obtained by nitrification under normal N_2 gas at 1373K for 2 hrs. The purity of produced TiC_0.7N_0.3 particles was above 99.3% and the oxygen contents below 0.2 wt%. We investigated in particular the effects of the temperatures in vacuum treatment on the particle refinement of final product.

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Synthesis of Ultrafine and Less Agglomerated TiCN Powders by Magnesiothermic Reduction
Dong-Won Lee
Journal of Korean Powder Metallurgy Institute.2012; 19(5): 356. CrossRef
Preparation of Ultrafine C/N Controled TiCxNyPowders by Magnesium Reduction
Dong-Won Lee, Byoung-Kee Kim, Jung-Yeul Yun, Ji-Hoon Yu, Yong-Jin Kim
Journal of Korean Powder Metallurgy Institute.2010; 17(2): 142. CrossRef

The Effect of Reduction Temperature on the Characteristic Variation of Niobium Powder During Metallothermic Reduction Process: Jae-Sik Yoon, Young-Mi Lee, Sun-Ho Hwang, Byung-Il Kim; J Korean Powder Metall Inst. 2009;16(2):104-109.; DOI: https://doi.org/10.4150/KPMI.2009.16.2.104

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Abstract PDF: Niobium powder was made from potassium heptafluoroniobite (K_2NbF_7) as the raw material using sodium (Na) as a reducing agent based on the hunter process. The apparatus for the experiment was designed and built specifically for the present study. The niobium particle size greatly increased as the reduction temperature increased from 710°C to 800°C. The particle size was fairly uniform, varying from 0.09µm to 0.4µm depending on the reduction temperatures. The niobium powder morphology and particle size are very sensitive to a reaction temperature in the metallothermic reduction process. The yield of niobium powder increased from 55% to 80% with a increasing a reaction temperature.

The Fabrication of PVA Polymer Coated on the Surface of B₄C Nanocomposite by High Energy Ball Mill: Young-Rang Uhm, Jae-Woo Kim, Jin-Woo Jung, Chang-Kyu Rhee; J Korean Powder Metall Inst. 2009;16(2):110-114.; DOI: https://doi.org/10.4150/KPMI.2009.16.2.110

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Mechanical coating process was applied to form 89 %-hydrolyzed poly vinyl alcohol (PVA) onto boron carbide (B_4C) nanopowder using one step high energy ball mill method. The polymer layer coated on the surface of B4C was changed to glass-like phase. The average particle size of core/shell structured B_4C/PVA was about 50 nm. The core/shell structured B_4C/PVA was formed by dry milling. However, the hydrolyzed PVA of 98sim99% with high glass transition temperature (T_g) was rarely coated on the powder. The T_g of polymer materials was one of keys for guest polymer coating on to the host powder by solvent free milling.

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Effect of Roasting Time and Cryogenic Milling on the Physicochemical Characteristics of Dried Ginseng Powder
Hayeong Jeong, Dong Hyeon Park, Han Geuk Seo, Mi-Jung Choi, Youngjae Cho
Foods.2020; 9(2): 223. CrossRef
The Effect of Milling Conditions for Dissolution Efficiency of Valuable Metals from PDP Waste Panels
Hyo-Seob Kim, Chan-Mi Kim, Chul-Hee Lee, Sung-Kyu Lee, Hyun-Seon Hong, Jar-Myung Koo, Soon-Jik Hong
Journal of Korean Powder Metallurgy Institute.2013; 20(2): 107. CrossRef
Characteristics of Indium Dissolution of Waste LCD Panel Powders Fabricated by High Energy Ball Milling (HEBM) Process with Milling Time
Hyo-Seob Kim, Jun-Je Sung, Cheol-Hee Lee, Hyun-Seon Hong, Soon-Jik Hong
Journal of Korean Powder Metallurgy Institute.2011; 18(4): 378. CrossRef
Refinement Behavior of Coarse Magnesium Powder by High Energy Ball Milling (HEBM)
Joon-Woo Song, Hyo-Seob Kim, Hong-Moule Kim, Taek-Soo Kim, Soon-Jik Hong
Journal of Korean Powder Metallurgy Institute.2010; 17(4): 302. CrossRef
Effect of Initial Silicon Scrap Size on Powder Refining Process During High Energy Ball Milling (HEBM)
Joon-Woo Song, Hyo-Seob Kim, Sung-Shin Kim, Jar-Myung Koo, Soon-Jik Hong
Journal of Korean Powder Metallurgy Institute.2010; 17(3): 242. CrossRef

Effects of Thermal Treatment Conditions on the Powder Characteristics of Uranium Oxide in HTGR Fuel Preparation: Yeon-Ku Kim, Kyung-Chai Jeong, Seung-Chul Oh, Dong-Soo Suhr, Moon-Sung Cho; J Korean Powder Metall Inst. 2009;16(2):115-121.; DOI: https://doi.org/10.4150/KPMI.2009.16.2.115

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The effects of thermal treatment conditions on ADU (ammonium diuranate) prepared by SOL-GEL method, so-called GSP (Gel supported precipitation) process, were investigated for UO_2 kernel preparation. In this study, ADU compound particles were calcined to UO_3 particles in air and Ar atmospheres, and these UO_3 particles were reduced and sintered in 4%-H_2/Ar. During the thermal calcining treatment in air, ADU compound was slightly decomposed, and then converted to UO_3 phases at 500°C. At 600°C, the U_3O_8 phase appeared together with UO_3. After sintering of theses particles, the uranium oxide phases were reduced to a stoichiometric UO_2. As a result of the calcining treatment in Ar, more reduced-form of uranium oxide was observed than that treated in air atmosphere by XRD analysis. The final phases of these particles were estimated as a mixture of U_3O_7 and U_4O_9.

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UO2 Spheres Produce by External Gelation Process
Yeon-Ku Kim, Injin Sah, Eung Seon Kim
Korean Journal of Materials Research.2020; 30(10): 533. CrossRef
Effects of Process Parameters on the Powder Characteristics of Uranium Oxide Kernel Prepared by Sol-gel Process
Yeon-Ku Kim, Kyung-Chai Jeong, Seung-Chul Oh, Dong-Soo Suhr, Moon-Sung Cho
Journal of Korean Powder Metallurgy Institute.2009; 16(4): 254. CrossRef

Fabrication and Characterization of ODS 316L Stainless Steels: Min-Ho Kim, Ho-Jin Ryu, Sung-Soo Kim, Chang-Hee Han, Jin-Sung Jang, Oh-Jong Kwon; J Korean Powder Metall Inst. 2009;16(2):122-130.; DOI: https://doi.org/10.4150/KPMI.2009.16.2.122

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Austenitic oxide-dispersion-strengthened (ODS) stainless steel was fabricated using a wet mixing process without a mechanical milling in order to reduce contaminations of impurities during their fabrication process. Solution of yttrium nitrate was dried after a wet mixing with 316L stainless steel powder. Carbon and oxygen contents were effectively reduced by this wet processing. Microstructural analysis showed that coarse yttrium silicates of about 150 nm were formed in austenitic ODS steels with a silicon content of about 0.8 wt%. Wet-processed austenitic ODS steel without silicon showed higher yield strength by the presence of finer oxide of about 20 nm.

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Dispersion Behaviors of Y2O3Particles Into Aisi 316L Stainless Steel by Using Laser Cladding Technology
Eun-Kwang Park, Sung-Mo Hong, Jin-Ju Park, Min-Ku Lee, Chang-Kyu Rhee, Kyeong-Won Seol, Yang-Kyu Lee
Journal of Korean Powder Metallurgy Institute.2013; 20(4): 269. CrossRef
Effects of the Sintering Variable on Impact Energy in MA 316L ODS and Wet 316L ODS Stainless Steels
Sung-Soo Kim, Chang-Hee Han, Jin-Sung Jang
Journal of Korean Powder Metallurgy Institute.2010; 17(2): 113. CrossRef

Effects of Surfactant and Preplate Process on Electroless Copper Plating on Carbon Nano-fiber: Jun-Hyun Han, Hyun-Kwang Seok, Sang-Soo Lee, Kwang-Koo Jee; J Korean Powder Metall Inst. 2009;16(2):131-137.; DOI: https://doi.org/10.4150/KPMI.2009.16.2.131

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Abstract PDF: This paper deals with the effects of the surfactant and preplate process (sensitization and activation) on electroless copper plating on carbon nano-fiber (CNF). Ultrasonic irradiation was applied both during dispersion of CNF and during electroless plating containing preplate process. The dispersion of CNF and flatness of the plated copper film were discussed based on the changes in surfactant concentration and preplate process time. It was clearly shown that high concentration of surfactant and long time of preplate process could promote the agglomeration of CNF and uneven copper plating on CNF.

Applications of Nanomanipulator in Nanowires: Sang-Won Yoon, Jong-Hyun Seo, Jae-Pyoung Ahn, Tae-Yeon Seong, Kon-Bae Lee; J Korean Powder Metall Inst. 2009;16(2):138-145.; DOI: https://doi.org/10.4150/KPMI.2009.16.2.138

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Abstract PDF: The combination of focused ion beam (FIB) and 4 point probe nanomanipulator could make various nano manufacturing and electrical measurements possible. In this study, we manufactured individual ZnO nanowire devices and measured those electrical properties. In addition, tensile experiments of metallic Au and Pd nanowires was performed by the same directional alignment of two nanomanipulators and a nanowire. It was confirmed from I-V curves that Ohmic contact is formed between electrodes and nanomanipulators, which is able to directly measure the electrical properties of a nanowire itself. In the mechanical tensile test, Au and Pd nanowires showed a totally different fracture behavior except the realignment from <110> to <002>. The deformation until the fracture was governed by twin for Au and by slip for Pd nanowires, respectively. The crystallographic relationship and fracture mechanism was discussed by TEM observations.

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