Journal of Powder Materials

Property Characterization and Analysis in Performance, Efficiency and Durability of the Membrane Electrode Assembly for Polymer Electrolyte Membrane Fuel Cell: Nam-In Kim, Han-Shin Choi, Hye-Sook Joo, Jun-Young Park; J Korean Powder Metall Inst. 2011;18(6):473-481.; DOI: https://doi.org/10.4150/KPMI.2011.18.6.473

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Fabrication and Tensile Properties of Alloy 617 base ODS Alloy: Hyoung-Kee Min, Suk-Hoon Kang, Tae-Kyu Kim, Chang-Hee Han, Do-Hyang Kim, Jin-Sung Jang; J Korean Powder Metall Inst. 2011;18(6):482-487.; DOI: https://doi.org/10.4150/KPMI.2011.18.6.482

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Abstract PDF: 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 700°C. 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: Byoung-Hwi Son, Jae-Geun Hong, Yong-Taek Hyun, Seung-Eon Kim, Seok-Choun Bae; J Korean Powder Metall Inst. 2011;18(6):488-495.; DOI: https://doi.org/10.4150/KPMI.2011.18.6.488

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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 µm and 300~425 µm respectively. NaCl of green Ti compact was removed in water followed by sintered at 1200°C 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.

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Investigation on the Structural and Mechanical Properties of Al Foam Manufactured by Spark Plasma Sintering and Compression Molding Methods
Seunghyeok Choi, Sang-Hwa Lee, Jae-Gil Jung, Seok-Jae Lee, Tae-Young Ahn, Yu-Song Choi, Seung Bae Son
Korean Journal of Metals and Materials.2024; 62(7): 533. CrossRef

Effect of Milling Time on the Microstructure and Phase Transformation Behaviors of Ni-B Powder During Mechanical Alloying Process: Jung-Geun Kim, Wook-Jin Lee, Sung-Kyun Park, Ik-Min Park, Yong-Ho Park; J Korean Powder Metall Inst. 2011;18(6):496-501.; DOI: https://doi.org/10.4150/KPMI.2011.18.6.496

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Abstract PDF: 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: Eun-Jung Lee, In-Hyuck Song, Jang-Hoon Ha, Yoo-Dong Hahn, Yang-Do Kim; J Korean Powder Metall Inst. 2011;18(6):502-509.; DOI: https://doi.org/10.4150/KPMI.2011.18.6.502

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Abstract PDF: 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/Al₂O₃ Catalyst for Selective Catalytic Reduction of NOx by Methane: Komateedi N. Rao, Chang-Yong Yu, Choi-Hee Lack, Heon-Phil Ha; J Korean Powder Metall Inst. 2011;18(6):510-516.; DOI: https://doi.org/10.4150/KPMI.2011.18.6.510

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In the present study, potassium and caesium doped Ag/Al_2O_3 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/Al_2O_3 and Cs-Ag/Al_2O_3 catalysts exhibited a promotional effect on deNOx activity in the presence of SO_2 and H_2O. The long-term isothermal studies at 550°C 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.

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Characteristics of Pt/C Nano-catalyst Synthesized by Arc Plasma Deposition
Hye-Sook Joo, Han-Shin Choi, Heon-Phil Ha, Do-Hyang Kim
Journal of Korean Powder Metallurgy Institute.2012; 19(1): 6. CrossRef

A Study on Remanufacturing of Deactivated Commercial Diesel Oxidation Catalyst by CVS-75 mode in Light Duty Diesel Engine: Chang-Hee Lee, Hea-Kyung Park; J Korean Powder Metall Inst. 2011;18(6):517-525.; DOI: https://doi.org/10.4150/KPMI.2011.18.6.517

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Abstract PDF: 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: Jung-Yeul Yun, Sang-Sun Yang, Hye-Young Koo, Hye-Moon Lee; J Korean Powder Metall Inst. 2011;18(6):526-531.; DOI: https://doi.org/10.4150/KPMI.2011.18.6.526

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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.

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Performance and techno-economic evaluation of a high-efficiency electrospray cyclone
Jun Su Park, Dae-Gyun Lee, Kang-San Lee, Jin-Han Kim, Jung Hoon Yoo, Hang Joo Shin, Young-Chan Choi, Young-joo Lee, YoungMin Woo, Meehye Lee, Jong Won Choi
Journal of Environmental Chemical Engineering.2024; 12(3): 112908. CrossRef
Electrospray and Thermal Treatment Process for Enhancing Surface Roughness of Fecralloy Coating Layer on a Large Sized Substrate
Hye Moon Lee, Hye Young Koo, Sangsun Yang, Dahee Park, Sooho Jung, Jung-Yeul Yun
Journal of Korean Powder Metallurgy Institute.2017; 24(1): 46. CrossRef
Alloyability of warm formed FeCrAl powder compacts
M.M. Rahman, A.A.A. Talib
Materials Today Communications.2015; 4: 42. CrossRef
Effect of Cell Size on the High Temperature Oxidation Properties of Fe-Cr-Al Powder Porous Metal Manufactured by Electro-spray Process
Jae-Sung Oh, Young-Min Kong, Byoung-Kee Kim, Kee-Ahn Lee
Journal of Korean Powder Metallurgy Institute.2014; 21(1): 55. CrossRef
Effect of Sintering Temperature on the High Temperature Oxidation of Fe-Cr-Al Powder Porous Metal Manufactured by Electrospray Process
Jae-Sung Oh, Young-Min Kong, Byoung-Kee Kim, Kee-Ahn Lee
Journal of Korean Powder Metallurgy Institute.2012; 19(6): 435. CrossRef

Synthesis and Catalytic Characteristics of Thermally Stable TiO₂/Pt/SiO₂ Hybrid Nanocatalysts: A. Satyanarayana Reddy, Chan-Ho Jung, Sun-Mi Kim, Jung-Yeul Yun, Jeong-Young Park; J Korean Powder Metall Inst. 2011;18(6):532-537.; DOI: https://doi.org/10.4150/KPMI.2011.18.6.532

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Abstract PDF: Thermally stable TiO_2/Pt/SiO_2 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/SiO_2 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 600°C 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: Jeong-Young Park, Sun-Mi Kim; J Korean Powder Metall Inst. 2011;18(6):538-545.; DOI: https://doi.org/10.4150/KPMI.2011.18.6.538

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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 O_2 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.

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Characteristics of Pt/C Nano-catalyst Synthesized by Arc Plasma Deposition
Hye-Sook Joo, Han-Shin Choi, Heon-Phil Ha, Do-Hyang Kim
Journal of Korean Powder Metallurgy Institute.2012; 19(1): 6. CrossRef

Microstructure and Synthesis of Ag Spot-coated Cu Nanopowders by Hydrothermal-attachment Method using Ag Colloid: Hyeong-Chul Kim, Jae-Kil Han; J Korean Powder Metall Inst. 2011;18(6):546-551.; DOI: https://doi.org/10.4150/KPMI.2011.18.6.546

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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.

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Synthesis and visible light photocatalytic activity of Ag spot-coated TiO2–60 wt% SrO composite powders
Hyeong-Chul Kim, Jae-Kil Han
Research on Chemical Intermediates.2014; 40(7): 2431. CrossRef
Microstructure and Synthesis of Nano Palladium Spot Coated Activated Carbon Powders by Hydrothermal Attachment Method
Hyeong Chul Kim, Jae Kil Han
Journal of Korean Powder Metallurgy Institute.2012; 19(6): 424. CrossRef

Effect of Heat Treatment Environment on the Properties of Cold Sprayed Cu-15 at.%Ga Coating Material for Sputtering Target: Byung-Chul Choi, Dong-Yong Park, Hyung-Jun Kim, Ik-Hyun Oh, Kee-Ahn Lee; J Korean Powder Metall Inst. 2011;18(6):552-561.; DOI: https://doi.org/10.4150/KPMI.2011.18.6.552

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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, 5%H_2+argon, pure argon, and vacuum were used in this study. Annealing treatments were conducted at 200sim800°C/1 hr. With the cold sprayed coating layer, pure alpha-Cu and small amounts of Ga_2O_3 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.

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Manufacturing of Large-Scale Cold-Sprayed Ta Target Material and Its Sputtering Property
Gi-Su Ham, Dong-Yeol Wi, Jun-Mo Yang, Kee-Ahn Lee
Journal of Thermal Spray Technology.2019; 28(8): 1974. CrossRef
Effect of Hot Isostatic Pressing on the Microstructure and Propertiesof Kinetic Sprayed Nb Coating Material
Ji-Hye Lee, Sangsun Yang, Kee-Ahn Lee
Journal of Korean Powder Metallurgy Institute.2016; 23(1): 15. CrossRef
Fabrication and Microstructure/Properties of Bulk-typeTantalum Material by a Kinetic Spray Process
Ji-Hye Lee, Ji-Won Kim, Kee-Ahn Lee
Journal of Korean Powder Metallurgy Institute.2016; 23(1): 8. CrossRef
Effect of Heat Treatment Environment on the Microstructure and Properties of Kinetic Sprayed Tantalum Coating Layer
Ji-Hye Lee, Hyung-Jun Kim, Kee-Ahn Lee
Journal of Korean Powder Metallurgy Institute.2015; 22(1): 32. CrossRef
The Effect of Annealing Heat Treatment on the Microstructure and Macroscopic Properties of Kinetic-Sprayed Ta Coating Layer
Myeong Ju Lee, Jae Sung Oh, Hyung Jun Kim, Ik Hyun Oh, Kee Ahn Lee
Advanced Materials Research.2014; 893: 64. CrossRef
Manufacturing of Cu Repair Coating Material Using the Kinetic Spray Process and Changes in the Microstructures and Properties by Heat Treatment
Min-Gwang Jeon, Hyung-Jun Kim, Kee-Ahn Lee
Journal of Korean Powder Metallurgy Institute.2014; 21(5): 349. CrossRef
Manufacturing and Properties of CGI-based Composite Coating Layer Utilizing a Warm Spray Process and Cu-Ga and Cu-In Mixed Powders
Min-Gwang Jeon, Myeong-Ju Lee, Hyeong-Jun Kim, Kee-Ahn Lee
Journal of Korean Powder Metallurgy Institute.2014; 21(3): 229. CrossRef
Effect of Heat Treatment Environment on the Densification of Cold Sprayed Ti Coating Layer
Ji-Sang Yu, Hyung-Jun Kim, Ik-Hyun Oh, Kee-Ahn Lee
Journal of Korean Powder Metallurgy Institute.2012; 19(2): 110. CrossRef
Sintering and Rolling Behavior of Cu-50In-13Ga Ternary Alloy Powder for Sputtering Target
Dae-Won Kim, Yong-Ho Kim, Jung-Han Kim, Dae-Guen Kim, Jong-Hyeon Lee, Kwang-Bo Choi, Hyeon-Taek Son
Journal of Korean Powder Metallurgy Institute.2012; 19(4): 264. CrossRef

The Effect of Sintering Processes and Additives on the Microstructures and Mechanical Properties of ZrB₂-SiC Composite Ceramics: Chang-Sup Kwon, Jung-Min Chae, Hyung-Tae Kim, Kyung-Ja Kim, Seong-Won Kim; J Korean Powder Metall Inst. 2011;18(6):562-567.; DOI: https://doi.org/10.4150/KPMI.2011.18.6.562

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This paper reports the effect of sintering processes and additives on the microstructures and mechanical properties of ZrB_2-SiC composite ceramics. We fabricated sintered bodies of ZrB_2-20 vol.% SiC with or without sintering additive, such as C or B_4C, 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 B_4C. With sintered bodies, mechanical properties, such as flexural strength and Vickers hardness, were also examined.

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Effect of the Size and Amount of SiC on the Microstructures and Thermal Conductivities of ZrB2-SiC Composite Ceramics
Seong-Won Kim, Chang-Sup Kwon, Yoon-Suk Oh, Sung-Min Lee, Hyung-Tae Kim
Journal of Korean Powder Metallurgy Institute.2012; 19(5): 379. CrossRef

Phase Evolution and Thermo-physical Properties of La₂(Zr_1-xHf_x)₂O₇ Oxides for Thermal Barrier Coatings: Seong-Won Kim, Sung-Min Lee, Yoon-Suk Oh, Hyung-Tae Kim, Byung-Koog Jang; J Korean Powder Metall Inst. 2011;18(6):568-574.; DOI: https://doi.org/10.4150/KPMI.2011.18.6.568

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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 La_2(Zr_1-xHf_x)_2O_7 pyrochlore systems are investigated for TBC applications. La_2(Zr_1-xHf_x)_2O_7 systems are comprised by selecting La3+ as A-site ions and Zr4+/Hf4+ as B-site ions in A_2B_2O_7 pyrochlore structures. For the developed phases in La_2(Zr_1-xHf_x)_2O_7 compositions, thermo-physical properties such as thermal conductivity, thermal expansion coefficient are examined. The potential of these La_2(Zr_1-xHf_x)_2O_7 compositions for TBC application is also discussed.

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Preparation of Suspension in La2O3-Gd2O3-ZrO2System via Planetary Mill and Characteristics of (La1-xGdx)2Zr2O7Coatings Fabricated via Suspension Plasma Spray
Chang-Sup Kwon, Sung-Min Lee, Yoon-Suk Oh, Hyung-Tae Kim, Byung-Koog Jang, Seongwon Kim
Journal of Korean Powder Metallurgy Institute.2013; 20(6): 453. CrossRef
Phase Evolution and Thermal Conductivities of (La1-xGdx)2Zr2O7Oxides for Thermal Barrier Coatings
Chang-Sup Kwon, Sung-Min Lee, Yoon-Suk Oh, Hyung-Tae Kim, Byung-Koog Jang, Seong Won Kim
Journal of Korean Powder Metallurgy Institute.2012; 19(6): 429. CrossRef

Investigation About Surface Microstructure of Aluminum with Change of Voltage, a Period of Treatment and Density of Electrolyte in Micro-Arc Oxidation Treatment: In-Chul Yeo, In-Cheol Kang; J Korean Powder Metall Inst. 2011;18(6):575-582.; DOI: https://doi.org/10.4150/KPMI.2011.18.6.575

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MAO(Micro-Arc Oxidation) method was used to make Al_2O_3 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.

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Control of Nano-Scaled Surface Microstructure of Al Sample for Improving Heat Release Ability
In-Chul Yeo, In-Cheol Kang
Journal of Korean Powder Metallurgy Institute.2015; 22(1): 21. CrossRef
Influence of MAO Conditions on TiO2Microstructure and Its Photocatalytic Activity
Jeong-Gon Kim, In-Cheol Kang
Journal of Korean Powder Metallurgy Institute.2012; 19(3): 196. CrossRef

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