Journal of Powder Materials

Powder Materials Used in Plasma Display Panel: Yong-Seog Kim; J Korean Powder Metall Inst. 2006;13(3):161-171.; DOI: https://doi.org/10.4150/KPMI.2006.13.3.161

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Ittt : ((()),,,((()), ((())) (Comparative Analysis of Chinese Western IT Manufacturing Cluster and its Implications: With Focus on the Chongqing, Chengdu, XiiAn)
Jonghyuk Oh, Hyun Jung Park
SSRN Electronic Journal.2014;[Epub] CrossRef
Ittt : ((()), ((()), ((())) (Comparative Analysis of Chinese Western IT Manufacturing Cluster and its Implications: With Focus on the Chongqing, Chengdu, XiiAn)
Jonghyuk Oh, Hyun Jung Park
SSRN Electronic Journal.2014;[Epub] CrossRef
Ittt : ((()), ((()), ((())) (Comparative Analysis of Chinese Western IT Manufacturing Cluster and Its Implications: With Focus on the Chongqing, Chengdu, Xi'An)
Jonghyuk Oh, Hyun Jung Park
SSRN Electronic Journal.2014;[Epub] CrossRef

Aging Characteristics of 7xxx Series Al Composites with Al₂O₃: Kyung-Ho Min, Kwang-Hyun Park, Young-Ik Seo, Si-Young Chang, Young-Do Kim; J Korean Powder Metall Inst. 2006;13(3):172-177.; DOI: https://doi.org/10.4150/KPMI.2006.13.3.172

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Abstract PDF: Aging characteristics and mechanical properties of commercial 7xxx series Al composites were investigated from viewpoint of ceramic contents. After sintering process, sintered densities of blended and composite powder were 95 and 97%, respectively. Each part was solution-treated at 475°C for 60 min and aged 175°C. And two-step aging was also performed form 120°C to 175°C. The aging behavior of the sintered composite pow-der was different from that of sintered blended powder. The peak aging time of the composite was rapid as well due to strain. Before aging, mechanical properties of sintered composite powder was significantly higher than that of sintered blended powder. These increments of properties were directly affected by ceramic particles. However, after aging, incremental rate of mechanical properties was slowed in the composite.

The Role of H₂O as PCA and the Precipitation Behavior in Mechanically Alloyed Ni-20Cr-20Fe-5Nb Alloy: Il-Ho Kim, S.I. Kwun, Won-Sik Lee, S.W. Chae, S.K. Hwang, M.H. Kim; J Korean Powder Metall Inst. 2006;13(3):178-186.; DOI: https://doi.org/10.4150/KPMI.2006.13.3.178

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Abstract PDF: The effect of use of H_2O as PCA(process control agent) to prevent the carbon contamination during mechanical alloying process and the precipitation behavior in Ni-20Cr-20Fe-5Nb bulk alloy after aging were investigated. NbC and Cr_2O_3 were formed during mechanical alloying and consolidation processes in the Ni-20Cr-20Fe-5Nb alloy in which methanol(CH_3OH) was added as PCA. Formation of NbC in this alloy decreased the amount of Nb dissolved in the Ni matrix. The use of H_2O as PCA in Ni-20Cr-20Fe-5Nb alloy prevented the formation of NbC and increased the hardness. The increase of hardness in this alloy was attributed to the increased amount of Nb dissolved in the Ni matrix. After aging treatment for 20 hours at 600°C;and;720°C of Ni-20Cr-20Fe-5Nb bulk alloy in which H_2O added as PCA, gamma"(Ni_3Nb,;tetragonal);and;delta;(Ni_3Nb,;orthorhombic) precipitates were formed, respectively. The precipitation temperatures of gamma" and delta in this bulk alloy were lower than those in commercial IN 718 alloy. It seemed that the lower precipitation temperatures for gamma" and delta in this bulk alloy than in commercial IN 718 alloy were due to severe plastic deformation during mechanical alloying.

The Fabrication of Al-Cu Alloy Nano Powders by a New Method Combining Electrodeposition and Electrical Wire Explosion: Je-Shin Park, Chang-Youl Suh, Han-Kwon Chang, Jae-Chun Lee, Won-Baek Kim; J Korean Powder Metall Inst. 2006;13(3):187-191.; DOI: https://doi.org/10.4150/KPMI.2006.13.3.187

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Abstract PDF: Al-Cu alloy nano powders were produced by the electrical explosion of Cu-plated Al wires. The composition and phase of the alloy could be controlled by varying the thickness of Cu deposit on Al wire. When the Cu layer was thin, Al solid solution and CuAl_2 were the major phases. As the Cu layer becomes thicker, Al diminished while Al_4Cu_9 phase prevailed instead. The average particle size of Al-Cu nano powders became slightly smaller from 63 nm to 44 nm as Cu layer becomes thicker. The oxygen content of Al-Cu powder decreased linearly with Cu content. It is well demonstrated that the electrodeposition combined with wire explosion could be simple and economical means to prepare variety of alloy and intermetallic nano powders.

Synthesis of Nanostructured Ceria Powders for an Oxygen-sensor by Thermochemical Process: Dong-Won Lee, Joon-Hwan Choi, Tae-Soo Lim, Yong-Jin Kim; J Korean Powder Metall Inst. 2006;13(3):192-198.; DOI: https://doi.org/10.4150/KPMI.2006.13.3.192

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Abstract PDF: The nanostructured cerium oxide powders were synthesized by spray thermal decomposition process for the use as the raw materials of resistive oxygen sensor. The synthesis routes consisted of 1) spray drying of water based organic solution made from cerium nitrate hydrate (Ce(NO_3)_36H_2O) and 2) heat treatment of spray dried precursor powders at 400°C in air atmosphere to remove the volatile components and identically to oxidize the cerium component. The produced powders have shown the loose structure agglomerated with extremely fine cerium oxide particles with about 15 nm and very high specific surface area (110m2/g). The oxygen sensitivity, n (LogproptoLog (P_O2/Po)-n and the response time, t_90 measured at 600°C in the sample sintered at 1000°C, were about 0.25 and 3 seconds, respectively, which had much higher performances than those known in micron or 100sim200nm sized sensors.

MicrostructuraL Characteristics During Hydrogen Desorption of Mechanical Milled TiH₂: S. Jung, Hyun-Sung Jung, Jae-Pyoung Ahn, Jong-Ku Park; J Korean Powder Metall Inst. 2006;13(3):199-204.; DOI: https://doi.org/10.4150/KPMI.2006.13.3.199

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Abstract PDF: We manufactured the metal hydrides of (Ti_0.88Mg_0.12)H_2 using a very easy and cheap way that Ti-12%Mg blending powder was mechanically milled with liquid milling media such as isopropyl alcohol (C_3H_8O, containing oxygen) and hexane (C_6H_14, no oxygen) as hydrogen source. The (Ti_0.88Mg_0.12)H_2 synthesized in isopropyl alcohol contained the high oxygen of 11.2%, while one in hexane had the low oxygen content of 0.7%. Such a difference of oxygen content affected the dehydriding behavior, phase transformation, and microstructural evolution at high temperature, which was investigated through X-ray diffraction and DSC measurements, and electron microscope observations.

The Effect of Composition on Hydrogen Reduction Behavior of Ball-milled WO₃-CuO Nanocomposite Powders: Sung-Soo Jung, Yun-Sung Kang, Jai-Sung Lee; J Korean Powder Metall Inst. 2006;13(3):205-210.; DOI: https://doi.org/10.4150/KPMI.2006.13.3.205

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The effect of Cu content on hydrogen reduction behavior of ball-milled WO_3-CuO nanocomposite powders was investigated. Hydrogen reduction behavior and reduction percent(alpha) of nanopowders were characterized by thermogravimetry (TG) and hygrometry measurements. Activation energy for hydrogen reduction of WO_3 nanopowders with different Cu content was calculated at each heating rate and reduction percent(alpha). The activation energy for reduction of WO_3 obtained in this study existed in the ranging from 129 to 139 kJ/mol, which was in accordance with the activation energy for WO_3 powder reduction of conventional micron-sized.

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Microstructural Feature of Full-densified W-Cu Nanocomposites Containing Low Cu Content
Jai-Sung Lee, Sung-Soo Jung, Joon-Phil Choi, Geon-Yong Lee
Journal of Korean Powder Metallurgy Institute.2013; 20(2): 138. CrossRef
Consolidation of Iron Nanopowder by Nanopowder-Agglomerate Sintering at Elevated Temperature
Jai-Sung Lee, Joon-Chul Yun, Joon-Phil Choi, Geon-Yong Lee
Journal of Korean Powder Metallurgy Institute.2013; 20(1): 1. CrossRef

Processing of Barrier Ribs of PDP Using an UV-curable Paste: Yoo-Seong Kim, Tae-Gum Koh, Yong-Seog Kim; J Korean Powder Metall Inst. 2006;13(3):211-216.; DOI: https://doi.org/10.4150/KPMI.2006.13.3.211

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Abstract PDF: In an attempt to reduce processing cost and to improve resolution of PDPs, micro mold transfer processing route for barrier ribs of plasma display panel was attempted. In this study, the parameters that may cause defects during the process were identified, which include the shrinkage during UV curing process, stress due to evaporation of organic components, and sintering shrinkage. Considering such parameters, UV curable paste was developed and barrier ribs of PDPs were successfully processed via the process. This work demonstrated the possibility of build-up route in manufacturing barrier ribs of PDP.

Effects of Applied Magnetic Field on the Electrical Properties of High Tc Superconductor: Sang-Heon Lee; J Korean Powder Metall Inst. 2006;13(3):217-222.; DOI: https://doi.org/10.4150/KPMI.2006.13.3.217

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Abstract PDF: The relationship between electrical properties of superconductor and externally applied magnetic field was studied to develop a magnetic field sensor. The electrical resistance of the superconductor was increased by applying external magnetic field and even after removal of the magnetic field. This behavior was related to the magnetic flux trapped in the superconductor, which penetrated through the material by the external magnetic field. Some portion of the superconductor was changed to a normal state by the trapped magnetic flux. The appearance of the normal state yielded to enhance the electrical resistance.

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