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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of Korean Powder Metallurgy Institute
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Journal DOI :
Korean Powder Metallurgy Institute
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Volume & Issues
Volume 18, Issue 6 - Dec 2011
Volume 18, Issue 5 - Oct 2011
Volume 18, Issue 4 - Aug 2011
Volume 18, Issue 3 - Jun 2011
Volume 18, Issue 2 - Apr 2011
Volume 18, Issue 1 - Feb 2011
Selecting the target year
Property Characterization and Analysis in Performance, Efficiency and Durability of the Membrane Electrode Assembly for Polymer Electrolyte Membrane Fuel Cell
Kim, Nam-In ; Choi, Han-Shin ; Joo, Hye-Sook ; Park, Jun-Young ;
Journal of Korean Powder Metallurgy Institute, volume 18, issue 6, 2011, Pages 473~481
DOI : 10.4150/KPMI.2011.18.6.473
Fabrication and Tensile Properties of Alloy 617 base ODS Alloy
Min, Hyoung-Kee ; Kang, Suk-Hoon ; Kim, Tae-Kyu ; Han, Chang-Hee ; Kim, Do-Hyang ; Jang, Jin-Sung ;
Journal of Korean Powder Metallurgy Institute, volume 18, issue 6, 2011, Pages 482~487
DOI : 10.4150/KPMI.2011.18.6.482
Alloy 617, Ni-22Cr-12Co-9Mo base oxide dispersion strengthened alloy was fabricated by using mechanical alloying, hot isostatic pressing and hot rolling. Uniaxial tensile tests were performed at room temperature and at
. Compared with the conventional Alloy 617, ODS alloy showed much higher yield strength and tensile strength, but lower elongation. Fracture surfaces of the tensile tested specimens were investigated in order to find out the mechanism of fracture mode at each test temperature. Grain adjustment during tensile deformation was analyzed by electron backscattered diffraction mapping, inverse pole figures and TEM observation.
Characteristics of Porous Titanium Fabricated by Space-holder Method using NaCl
Son, Byoung-Hwi ; Hong, Jae-Geun ; Hyun, Yong-Taek ; Kim, Seung-Eon ; Bae, Seok-Choun ;
Journal of Korean Powder Metallurgy Institute, volume 18, issue 6, 2011, Pages 488~495
DOI : 10.4150/KPMI.2011.18.6.488
This study was performed to fabricate the porous titanium foam by space holder method using NaCl powder, and to evaluate the effect of NaCl volume fractions (33.3~66.6 vol.%) on the porosities, compressive strength, Young's modulus and permeability. For controlling pore size, CP titanium and NaCl particles were sieved to different size range of 70~150
respectively. NaCl of green Ti compact was removed in water followed by sintered at
for 2 hours. Total porosities of titanium foam were in the range of 38-70%. Pore shape was a regular hexahedron similar that of NaCl shape. Porous Ti body showed that Young's modulus and compressive strength were in the range of 0.6-6 GPa and 8-127 MPa respectively. It showed that pore size and mechanical properties of Ti foams was controllable by NaCl size and volume fractions.
Effect of Milling Time on the Microstructure and Phase Transformation Behaviors of Ni-B Powder During Mechanical Alloying Process
Kim, Jung-Geun ; Lee, Wook-Jin ; Park, Sung-Kyun ; Park, Ik-Min ; Park, Yong-Ho ;
Journal of Korean Powder Metallurgy Institute, volume 18, issue 6, 2011, Pages 496~501
DOI : 10.4150/KPMI.2011.18.6.496
In this study, the effect of milling time on the microstructure and phase transformation behaviors of Ni-12 wt.%B powders was investigated using vibratory ball milling process. X-ray diffraction patterns showed that the phase transformation of mixed Ni-B elemental powder occurred after 50 hours of milling, with a formation of nickel boride phases. Through the study of microstructures in mechanical alloying process, it was considered that ball milling strongly accelerates solid-state diffusions of the Ni and B atoms during mechanical alloying process. The results of X-ray photoelectron spectroscopy showed that most of B atoms in the powder were linked to Ni with a formation of nickel boride phases after 200 hours of milling. It was finally concluded that mechanical alloying using ball milling process is feasible to synthesize fine and uniform nickel boride powders.
Effect of Pore Formers and Sintering Temperatures on Microstructure and Bending Strength of the Porous Zirconia Ceramics
Lee, Eun-Jung ; Song, In-Hyuck ; Ha, Jang-Hoon ; Hahn, Yoo-Dong ; Kim, Yang-Do ;
Journal of Korean Powder Metallurgy Institute, volume 18, issue 6, 2011, Pages 502~509
DOI : 10.4150/KPMI.2011.18.6.502
In this study, a novel-processing route for fabricating microcellular zirconia ceramics has been developed. The proposed strategy for making the microcellula zirconia ceramics involved hollow microspheres as pore former. Compared to conventional dense microspheres pore former, well-defined pore structured zirconia ceramics were successfully fabricated. Effects of hollow microsphere content and sintering temperature on microstructure, porosity, pore distribution, and strength were investigated in the processing of microcellular zirconia ceramics.
K and Cs Doped Ag/Al
Catalyst for Selective Catalytic Reduction of NOx by Methane
Rao, Komateedi N. ; Yu, Chang-Yong ; Lack, Choi-Hee ; Ha, Heon-Phil ;
Journal of Korean Powder Metallurgy Institute, volume 18, issue 6, 2011, Pages 510~516
DOI : 10.4150/KPMI.2011.18.6.510
In the present study, potassium and caesium doped Ag/
catalysts were synthesized by simple wet impregnation method and evaluated for selective catalytic reduction (SCR) of NOx using methane. TEM analysis and diffraction patterns demonstrated the finely dispersed Ag particles. BET surface measurements reveal that the prepared materials have moderate to high surface area and the metal amount found from ICP analysis was well matching with the theoretical loadings. The synthesized K-Ag/
catalysts exhibited a promotional effect on deNOx activity in the presence of
. The long-term isothermal studies at
under oxygen rich condition showed the superior catalytic properties of the both alkali promoted samples. The crucial catalytic properties of materials are attributed to NO adsorption properties detected by the NO TPD.
A Study on Remanufacturing of Deactivated Commercial Diesel Oxidation Catalyst by CVS-75 mode in Light Duty Diesel Engine
Lee, Chang-Hee ; Park, Hea-Kyung ;
Journal of Korean Powder Metallurgy Institute, volume 18, issue 6, 2011, Pages 517~525
DOI : 10.4150/KPMI.2011.18.6.517
In this study, the used DOCs, which could remove the air pollutants such as CO and HC in the exhaust gas from diesel vehicle, were remanufactured by various conditions. Their catalytic performances and characterization were also investigated. The remanufacturing process of the deactivated DOCs includes high temperature cleaning of incineration, ultrasonic cleaning for washing with acid/base solutions to remove deactivating materials deposited to the surface of the catalysts, and active component reimpregnation for reactivating catalytic activity of them. The catalytic performance tests of the remanufactured DOCs were carried out by the diesel engine dynamo systems and chassi dynamo systems in CVS-75 mode. All prepared catalysts were characterized by the optical microscopes, SEM, EDX, porosimeter and BET to investigate correlations between catalytic reactivity and surface characteristics of them. The remanufactured DOCs at various conditions showed the improved catalytic performances reaching to 90% of fresh DOC, which is attributed to remove the deactivating materials from the surface of the used DOC through the analysis of catalytic performance test and their characterization.
Fabrication of Fecralloy Foil Coated by Fecralloy Nanoparticles Using Electrospray Processing
Yun, Jung-Yeul ; Yang, Sang-Sun ; Koo, Hye-Young ; Lee, Hye-Moon ;
Journal of Korean Powder Metallurgy Institute, volume 18, issue 6, 2011, Pages 526~531
DOI : 10.4150/KPMI.2011.18.6.526
Fecralloy is the promising materials for high temperature exhaust filtering system due to the excellent its oxidation resistance property. In this research, Fecralloy nanoparticles coated Fecralloy thin foil was prepared by a single nozzle electrospray system in order to increase surface area of Fecralloy foil. Fecralloy nanoparticles were fabricated by electrical wire explosion method in ethanol using Fecralloy wires as a source material. Electrospray modes with applied D.C voltages to Fecralloy colloidal solution were investigated to make a stable cone-jet mode. Coated layers with and without additional heat treatment were observed by FE-SEM (field emission-scanning electron microscope) and tape test for evaluating their adhesion to substrate were performed as well.
Synthesis and Catalytic Characteristics of Thermally Stable TiO
Reddy, A. Satyanarayana ; Jung, Chan-Ho ; Kim, Sun-Mi ; Yun, Jung-Yeul ; Park, Jeong-Young ;
Journal of Korean Powder Metallurgy Institute, volume 18, issue 6, 2011, Pages 532~537
DOI : 10.4150/KPMI.2011.18.6.532
core-shell nanocatalyst has been synthesized by chemical processes. Citrated capped Pt nanoparticles were deposited on amine functionalized silica produced by Stober process. Ultrathin layer of titania was coated on Pt/
for preventing sintering of the metal nanoparticles at high temperatures. Thermal stability of the metal-oxide hybrid catalyst was demonstrated heating the sample up to
in air and by investigating the morphology and integrity of the structure by transmission electron spectroscopy. The surface analysis of the constituent elements was performed by X-ray photoemission spectroscopy. The catalytic activity of the hybrid catalysts was investigated by CO oxidation reaction with oxygen as a model reaction.
Investigation of Catalytic Activity Through Controlling Its Size and Composition of RhPt Bimetallic Nanoparticles
Park, Jeong-Young ; Kim, Sun-Mi ;
Journal of Korean Powder Metallurgy Institute, volume 18, issue 6, 2011, Pages 538~545
DOI : 10.4150/KPMI.2011.18.6.538
This study shows that catalytic activity of bimetallic RhPt nanoparticle arrays under CO oxidation can be tuned by varying the size and composition of nanoparticles. The tuning of size of RhPt nanoparticles was achieved by changing concentration of rhodium and platinum precursors in one-step polyol synthesis. Two-dimensional RhPt bimetallic nanoparticle arrays in different size and composition were prepared through Langmuir-Blodgett thin film technique. CO oxidation was carried out on these two-dimensional nanoparticle arrays, revealing higher activity on the smaller nanoparticles compared to the bigger nanoparticles. X-ray photoelectron spectroscopy (XPS) results indicate the preferential surface segregation of Rh compared to Pt on the smaller nanoparticles, which is consistent with the thermodynamic analysis. Because the catalytic activity is associated with differences in the rates of
dissociative adsorption between Pt and Rh, this paper suppose that the surface segregation of Rh on the smaller bimetallic nanoparticles is responsible for the higher catalytic activity in CO oxidation. This result suggests a control mechanism of catalytic activity via synthetic approaches of colloid nanoparticles, with possible application in rational design of nanocatalysts.
Microstructure and Synthesis of Ag Spot-coated Cu Nanopowders by Hydrothermal-attachment Method using Ag Colloid
Kim, Hyeong-Chul ; Han, Jae-Kil ;
Journal of Korean Powder Metallurgy Institute, volume 18, issue 6, 2011, Pages 546~551
DOI : 10.4150/KPMI.2011.18.6.546
Ag spot-coated Cu nanopowders were synthesized by a hydrothermal-attachment method (HA) using oleic acid capped Ag hydrosol. Cu nano powders were synthesized by pulsed wire exploding method using 0.4 mm in diameter of Cu wire (purity 99.9%). Synthesized Cu nano powders are seen with comparatively spherical shape having range in 50 nm to 150 nm in diameter. The oleic acid capped Ag hydrosol was synthesized by the precipitation-redispersion method. Oleic acid capped Ag nano particles showed the narrow size distribution and their particle size were less than 20 nm in diameter. In the case of nano Ag-spot coated Cu powders, nanosized Ag particles were adhered in the copper surface by HAA method. The components of C, O and Ag were distributed on the surface of copper powder.
Effect of Heat Treatment Environment on the Properties of Cold Sprayed Cu-15 at.%Ga Coating Material for Sputtering Target
Choi, Byung-Chul ; Park, Dong-Yong ; Kim, Hyung-Jun ; Oh, Ik-Hyun ; Lee, Kee-Ahn ;
Journal of Korean Powder Metallurgy Institute, volume 18, issue 6, 2011, Pages 552~561
DOI : 10.4150/KPMI.2011.18.6.552
This study attempted to manufacture a Cu-15 at.%Ga coating layer via the cold spray process and investigated the effect of heat treatment environment on the properties of cold sprayed coating material. Three kinds of heat treatment environments,
+argon, pure argon, and vacuum were used in this study. Annealing treatments were conducted at
/1 hr. With the cold sprayed coating layer, pure
-Cu and small amounts of
were detected in the XRD, EDS, EPMA analyses. Porosity significantly decreased and hardness also decreased with increasing annealing temperature. The inhomogeneous dendritic microstructure of cold sprayed coating material changed to the homogeneous and dense one (microstructural evolution) with annealing heat treatment. Oxides near the interface of particles could be reduced by heat treatment especially in vacuum and argon environments. Vacuum environment during heat treatment was suggested to be most effective one to improve the densification and purification properties of cold sprayed Cu-15 at.%Ga coating material.
The Effect of Sintering Processes and Additives on the Microstructures and Mechanical Properties of ZrB
-SiC Composite Ceramics
Kwon, Chang-Sup ; Chae, Jung-Min ; Kim, Hyung-Tae ; Kim, Kyung-Ja ; Kim, Seong-Won ;
Journal of Korean Powder Metallurgy Institute, volume 18, issue 6, 2011, Pages 562~567
DOI : 10.4150/KPMI.2011.18.6.562
This paper reports the effect of sintering processes and additives on the microstructures and mechanical properties of
-SiC composite ceramics. We fabricated sintered bodies of
-20 vol.% SiC with or without sintering additive, such as C or
, densified by spark plasma sintering as well as hot pressing. While almost full densification was achieved regardless of sintering processes or sintering additives, significant grain growth was observed in the case of spark plasma sintering, especially with
. With sintered bodies, mechanical properties, such as flexural strength and Vickers hardness, were also examined.
Phase Evolution and Thermo-physical Properties of La
Oxides for Thermal Barrier Coatings
Kim, Seong-Won ; Lee, Sung-Min ; Oh, Yoon-Suk ; Kim, Hyung-Tae ; Jang, Byung-Koog ;
Journal of Korean Powder Metallurgy Institute, volume 18, issue 6, 2011, Pages 568~574
DOI : 10.4150/KPMI.2011.18.6.568
As operating temperatures of engines or turbines continually increase for higher efficiency, significant amounts of researches have been focused on finding new materials, which would be alternatives to conventional yttria-stabilized zirconia (YSZ) for thermal barrier coatings (TBCs). In this study, phase evolution and thermo-physical properties of
pyrochlore systems are investigated for TBC applications.
systems are comprised by selecting
as A-site ions and
as B-site ions in
pyrochlore structures. For the developed phases in
compositions, thermo-physical properties such as thermal conductivity, thermal expansion coefficient are examined. The potential of these
compositions for TBC application is also discussed.
Investigation About Surface Microstructure of Aluminum with Change of Voltage, a Period of Treatment and Density of Electrolyte in Micro-Arc Oxidation Treatment
Yeo, In-Chul ; Kang, In-Cheol ;
Journal of Korean Powder Metallurgy Institute, volume 18, issue 6, 2011, Pages 575~582
DOI : 10.4150/KPMI.2011.18.6.575
MAO(Micro-Arc Oxidation) method was used to make
surface on 6063 Al specimen. This study was focused on an influence of voltage, density of electrolyte and a period of treatment on the change of surface microstructure by using SEM(Scanning Electron Microscope), EDS(Energy Dispersive X-ray Spectroscopy). The microstructure shows higher roughness and thicker oxidized layer with increase of voltage and maintaining period of treatment. The density of electrolyte affected a formation of more dense surface and increase of a oxidized layer.