Journal of Powder Materials

Development Trends and Perspectives of Dye-Sensitized Solar Cells: Moon-Sung Kang , Yong-Soo Kang; J Korean Powder Metall Inst. 2005;12(1):7-16.; DOI: https://doi.org/10.4150/KPMI.2005.12.1.007

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Abstract PDF: Dye-sensitized solar cells(DSSCs) have been under investigation for the past decade due to their attractive features such as high energy conversion efficiency and low production costs. The basis for energy conversion in the injection of electrons from a photoexcited stateof a dye sensitizer into the conduction band of the nanocrystalline TiO_2 semiconductor upon absorption of light. It is believed that the DSSC is one of the most promising technologies to solve the significant energy problems. In this article, the development trends and perspective of DSSCs were reviewed.

Fabrication and Mechanical Properties of Dense WSi₂-20vol.%SiC Composite by High-Frequency Induction-Heated Combustion Synthesis: Dong-Young Oh, Hwan-Cheol Kim, Sang-Kwon Lee, In-Jin Shon; J Korean Powder Metall Inst. 2005;12(1):17-23.; DOI: https://doi.org/10.4150/KPMI.2005.12.1.017

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Abstract PDF: Dense WSi_2-20vol.%SiC composite was synthesized by high-frequency induction-heated combustion synthesis(HFIHCS) method within 2 minutes in one step from elemental powder mixture of W, Si and C. Simultaneous combustion synthesis and densification were accomplished under the combined effects of an induced current and mechanical pressure. Highly dense WSi_2-20vol.%SiC with relative density of up to 97% was produced under simultaneous application of 60MPa pressure and the induced current. The average grain size of WSi_2 was about 5.2µm. The hardness and fracture toughness values obtained were 1700kg/mm2 and 4.4MPacdotm1/2, respectively.

Dynamic Compaction of Mechanochemically Alloyed Fe-Si Nano Powders by Magnetic Pulsed Pressure: G.-H. Lee, C.-K. Rhee, W.-W. Kim, J.-W. Yun, K.-S. Lee; J Korean Powder Metall Inst. 2005;12(1):24-29.; DOI: https://doi.org/10.4150/KPMI.2005.12.1.024

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Nano Fe-6.5wt%Si powders have been synthesized by mechano-chemical process (MCP) for an application of soft magnetic core. Owing to hard and brittle characteristics of Fe-6.5Si nano powders having large surface area, it is very difficult to reach high density more than 70% of theoretical density (~7.4 g/cm_3) by cold compaction. To overcome such problem a magnetic pulsed compaction (MPC), which is one of dynamic compaction techniques, was applied. The green density was achieved about 78% (~5.8 g/cm_3) by MPC at room temperature.

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Microstructure and Characteristics of Ag-SnO2Contact Materials Prepared by Magnetic Pulsed Compaction
J.S. Park, Y.J. Kim, M.H. Lee, H.S. Lee, S.J. Hong, J.K. Lee
Journal of Korean Powder Metallurgy Institute.2011; 18(4): 372. CrossRef

Accumulative Roll-Bonding of Al Powder Compact Fabricated by a Powder-in Sheath Rolling Method: Seong-Hee Lee; J Korean Powder Metall Inst. 2005;12(1):30-35.; DOI: https://doi.org/10.4150/KPMI.2005.12.1.030

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Abstract PDF: An aluminum powder compact consolidated by a powder-in sheath rolling (PSR) method was severely deformed by accumulative roll-bonding (ARB) process. The ARB process was performed up to 8 cycles at ambient temperature without lubrication. Optical microscope and transmission electron microscope observations revealed that microstructure of the ARB-processed Al powder compact is inhomogeneous in the thickness direction. The ultra-fine subgrains often reported in the ARB-processed bulky materials were also developed near surface of the Al powder compacts in this study. Tensile strength of the ARB-processed Al powder compact increased at the 1st cycle, but from the 2nd cycle it rather decreased slightly.

Phase Transformation in Al-4at.%Zr Alloy during Mechanical Alloying and Heat-treatment Processes: Jae-Pil Park, Il-Ho Kim, S.I. Kwun; J Korean Powder Metall Inst. 2005;12(1):36-42.; DOI: https://doi.org/10.4150/KPMI.2005.12.1.036

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Abstract PDF: Four different mechanical alloying(MA) processes were employed to fabricate very fine intermetallic compound Al_3Zr particles dispersed Al composite materials(MMC) with Al-4at.%Zr composition. Phase transformations including phase stability during MA and heat treatment processes were investigated. Part of Zr atoms were dissolved into Al matrix and part of them reacted with hydrogen produced by decomposition of PCA(methanol) to form hydride ZrH_2 during first MA process. These ZrH_2 hydrides disappeared when alloy powders were heat treated at 500circC. Stable Al_3Zr dispersoids with DO_23 structure were formed by heat treating the mechanically alloyed powders at 400circC. On the other hand, metastable Al_3Zrdispersoids with L1_2 structure were formed during first MA of powers with Al-25at.%Zr composition. These metastable Al_3Zr dispersoids transformed to stable Al_3Zr with DO_23 structure when heat treated above 450circC.

Thermal Stability of Al-Fe-X Alloy System Prepared by Mechanical Alloying and Spark Plasma Sintering: II. Al-Fe-Cr and Al-Fe-Mo: Hyun-Kwuon Lee, Sang-Woo Lee, Kyeong-Sik Cho; J Korean Powder Metall Inst. 2005;12(1):43-50.; DOI: https://doi.org/10.4150/KPMI.2005.12.1.043

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Mechanical alloying using high-energy ball mill and subsequent spark plasma sintering (SPS) process was applied to Al-Fe-Cr and Al-Fe-Mo powder mixture to investigate effects of Cr and Mo addition on thermal stability of Al-Fe, and thereby to enhance its thermal stability up to 500circC. Various analytical techniques including micro-Vickers hardness test, SEM, TEM, X-ray diffractometry and corrosion test were carried out. It was found that addition of Cr and Mo to Al-Fe system played a role of grain growth inhibitor of matrix Al and some precipitates such as Al_3Fe during SPS and subsequent heat treatment. The inhibition of grain growth resulted in increased Vickers hardness and thermal stability up to 500circC comparing to those of Al-Fe alloy system.

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A Constitutional Framework of a Future Palestinian State - Synthesis of Leading Palestinian Thinking and Public Perceptions
Asem Khalil
SSRN Electronic Journal.2009;[Epub] CrossRef

Study on the Properties of Catalase Activity Using Cuprite Nano-Particles Synthesized by Hydrolysis Method: Y.-R. Uhm, W.-W. Kim, J.-S. Oh, C.-K. Rhee; J Korean Powder Metall Inst. 2005;12(1):51-55.; DOI: https://doi.org/10.4150/KPMI.2005.12.1.051

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Abstract PDF: Cu_2O nano cubes with high catalase activity were synthesized by reduction of freshly prepared Cu in distilled water at 40circC and their catalase activities of H_2O_2 were studied. Transmission electron microscopy (TEM) observation showed that most of these nanocubes were uniform in size, with the average edge length of 30 nm. Selected area electron diffraction of TEM revealed that the nanocube consisted of single crystalline Cu_2O, but it changed to CuO phase. The catalase activity depends on the amount of both cuprite phase and surface area.

Preparation of Ag Powder from AgNO₃ by Wet Chemical Reduction Method1. The Establishment of Optimum Reaction System for the Preparation of Spherical Ag Powder: Ki-Seok Yuna, Young-Chul Park, Beom-Seok Yang, Hyun-Hong MIn, Chang-Whan Won; J Korean Powder Metall Inst. 2005;12(1):56-63.; DOI: https://doi.org/10.4150/KPMI.2005.12.1.056

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Ag powder was prepared from AgNO_3 by wet chemical reduction method using various reduction agent system involving AgNO_3, AgNO_2(AgCl) and Ag complex ion aqueous solution. The pure Ag powder could be prepared regardless of reaction system but the particle shape and distribution were affected very much according to the kind of reduction agents and reaction systems. The optimum reaction system for the preparation of the silver powder having the uniform particle shape and size distribution was Ag complex ion aqueous solution-reduction agent system and in particular, H_2O_2 and C_6H_8O_6as a reduction agent leaded the more uniform particle shape and size distribution.

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Effect of chloride ion on synthesis of silver nanoparticle using retrieved silver chloride as a precursor from the electronic scrap
Juyeon Yoo, Hyeongsub So, MinHo Yang, Kun-Jae Lee
Applied Surface Science.2019; 475: 781. CrossRef

Study on the Catalytic Properties of Copper Oxide Nanoparticles Synthesized by Levitational Gas Condensation (LGC) Method: Y.-R. Uhm, W.-W. Kim, J.-S. Oh, C.-K. Rhee; J Korean Powder Metall Inst. 2005;12(1):64-69.; DOI: https://doi.org/10.4150/KPMI.2005.12.1.064

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Abstract PDF: The copper oxide nano powders were synthesized by levitational gas condensation(LGC) method, and their high heterogeneous catalytic effects of oxidation of 2,3,5-trimethyl-1,4- hydroquinone (TMHQ) and catalase activity were studied. The observation of transmission electron microscopy (TEM) shows that most of these nano powders are uniform in size, with the average particle size of 35 nm. The nano powder consists of mainly Cu_2O, but it is aged to CuO phase. The catalytic effect which was clarified by oxidation of TMHQ and catalase depends on the amount of cuprite phase and the particle size.

Thermal Stability of Al-Fe-X Alloy System Prepared by Mechanical Alloying and Spark Plasma Sintering: I. Al-Fe: Hyun-Kwuon Lee, Sang-Woo Lee, Kyeong-Sik Cho; J Korean Powder Metall Inst. 2005;12(1):70-78.; DOI: https://doi.org/10.4150/KPMI.2005.12.1.070

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Mechanical alloying using high-energy ball mill and subsequent spark plasma sintering (SPS) process was applied to understand mechanical alloying processing of Al-Fe alloy system. The thermal stability of mechanically alloyed Al-Fe alloy was intended to be enhanced by SPS process. Various analytical techniques including particle size analysis, density measurement, micro-Vickers hardness test, SEM, TEM, and X-ray diffractometry were adopted to find optimum processing conditions for mechanical alloying and subsequent SPS and to estimate thermal stability of the prepared alloy. It was found from the treatment of mechanically alloyed Al-8wt.%Fe powder mixture that needle-shaped Al_3Fe precipitates was formed in the Al-Fe matrix, and the alloy compact showed enhanced densification and reached its full density with little loss of its fine microstructure. After heat treatment at 500circC, it was also shown that the thermal stability of Al-8wt.%Fe alloy fabricated in the present study was enhanced, which was due to its fine microstructure developed by fast densification of SPS.

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Effect of Sintering Temperature on Microstructure and Mechanical Properties for the Spark Plasma Sintered Titanium from CP-Ti Powders
Kyeong-Sik Cho, In-Beom Song, Min-Hyeok Jang, Ji-Hye Yoon, Myung-Hoon Oh, Jae-Keun Hong, Nho-Kwang Park
Journal of Korean Powder Metallurgy Institute.2010; 17(5): 365. CrossRef

셰계 다이아몬드 공구의 역사를 다시 쓴다;세계초일류기업의 세계초일류 기술: Shinhandia,; J Korean Powder Metall Inst. 2005;12(1):79-81.; DOI: https://doi.org/10.4150/KPMI.2005.12.1.079

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