Journal of Powder Materials

Chul-Jin Choi

6 Articles

Production and Application of Nanoparticles by the Chemical Vapor Condensation Process: Jin-Chun Kim, Gook-Hyun Ha, Chul-Jin Choi, Byoung-Kee Kim; J Korean Powder Metall Inst. 2005;12(4):239-248.; DOI: https://doi.org/10.4150/KPMI.2005.12.4.239

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Synthesize of Nd₂Fe₁₄B Powders from 1-D Nd₂Fe₁₄B Wires using Electrospinning Process
Nu Si A Eom, Su Noh, Muhammad Aneeq Haq, Bum Sung Kim
Journal of Korean Powder Metallurgy Institute.2019; 26(6): 477. CrossRef

Microstructure and Sintering Behavior of Injection Molded Fe Sintered Body Using Rapid Thermal Heating Process: Ki-Hyun Kim, Jae-Kil Han, Ji-Hun Yu, Chul-Jin Choi, Byong-Taek Lee; J Korean Powder Metall Inst. 2004;11(6):528-534.; DOI: https://doi.org/10.4150/KPMI.2004.11.6.528

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Abstract PDF: Using the nano Fe powders having 50 nm in diameter, Fe compact bodies were fabricated by injec-tion molding process. The relationship between microstructure and material properties depending on the volume ratio of powder/binder and sintering temperature were characterized by SEM, TEM techniques. In the compact body with the volume percentage ratio of 45(Fe powder) : 55(binder), which was sintered at 700°C, the relative density was about 97%, and the values of volume shrinkage and hardness were about 66.3% and 242.0 Hv, respec-tively. Using the composition of 50(Fe powder) : 50(binder) and sintered at 700°C, the values of relative density, volume shrinkage and hardness of Fe sintered bodies were 73.3%,;47.6% and 152.8 Hv, respectively. They showed brittle fracture mode due to the porous and fine microstructure.

Characterization of Fe Nanocapsules synthesized by Plasma Arc Discharge Process: Woo-Young Park, Cheol-Su Youn, Ji-Hun Yu, Young-Woo Oh, Chul-Jin Choi; J Korean Powder Metall Inst. 2004;11(6):510-514.; DOI: https://doi.org/10.4150/KPMI.2004.11.6.510

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Abstract PDF: Iron-carbon nanocapsules were synthesized by plasma arc discharge (PAD) process under various atmosphere of methane, argon and hydrogen gas. Characterization and surface properties were investigated by means of HRTEM, XRD, XPS and Mossbauer spectroscopy. Fe nanocapsules synthesized were composed of three phases (alpha-Fe,;Y-Fe;and;Fe_3C) with core/shell structures. The surface of nanocapsules was covered by the shell of graphite phase in the thickness of 4~5nm.

Preparation of FeAl nanopowders by Plasma Arc Discharge Process: Woo-Young Park, Cheol-Su Youn, Ji-Hun Yu, Young-Woo Oh, Chul-Jin Choi; J Korean Powder Metall Inst. 2004;11(6):522-527.; DOI: https://doi.org/10.4150/KPMI.2004.11.6.522

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Abstract PDF: Nano sized FeAl intermetallic particles were successfully synthesized by plasma arc discharge pro-cess. The synthesized powders shouted core-shell structures with the particle size of 10-20 nm. The core was metallic FeAl and shell was composed of amorphous AI_2O_3;and;a;little;amount;of;metallic;Fe_3O_4. Because of the difference of Fe and Al vapor pressure during synthesis, the Al contents in the nanoparticles depended on the Al contents of master alloy.

Fabrication of Injection Molded Fe-50%Ni Sintered Bodies: Ki-Hyun Kim, Hyeong-Chul Yoon, Chul-Jin Choi, Byong-Taek Lee; J Korean Powder Metall Inst. 2004;11(6):472-476.; DOI: https://doi.org/10.4150/KPMI.2004.11.6.472

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The Fe-Ni compact bodies were fabricated using Fe-Ni mixed powders with 50 nm in diameter by injection molding process. The relationship between microstructure and material properties was characterized with respect to the volume ratio of powder/binder and sintering temperature with SEM and TEM. In the compact body having the volume percent ratio of 45(Fe-Ni) : 55(binder), which was sintered at 900°C the values of relative density and hardness were low about 97.7% and 277.1 Hv, respectively. Using the composition of 50(Fe Ni) : 50(binder) and sintered at 900°C, the values of relative density and hardness were 98.5%, 294.4 Hv, respec-tively. The grain size of sintered bodies strongly depended on the sintering temperature. In both samples sintered at 600°C and 900°C, the average grain sizes were about 150 nm and 500 nm in diameter, respectively.

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Microstructure and High Temperature Oxidation Behaviors of Fe-Ni Alloys by Spark Plasma Sintering
Chae Hong Lim, Jong Seok Park, Sangsun Yang, Jung-Yeul Yun, Jin Kyu Lee
Journal of Korean Powder Metallurgy Institute.2017; 24(1): 53. CrossRef

Synthesis and Microstructure of Fe(C) Nanocapsules by Chemical Vapor Condensation: Jung-Han Lee, Sung-Duk Kim, Jin-Chun Kim, Chul-Jin Choi, Chan-Gyu Lee; J Korean Powder Metall Inst. 2004;11(6):515-521.; DOI: https://doi.org/10.4150/KPMI.2004.11.6.515

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Abstract PDF: Fe(C) nanocapsules were prepared by the chemical vapor condensation(CVC) process using the pyrolysis of iron pentacarbonyl (Fe(CO)_5). Their characterizations were studied by means of X-ray diffraction, X-ray photoelectron spectrometer and transmission electron microscopy. The long-chained Fe(C) nanocapsules hav-ing the mean size of under 70 nm could be obtained below 1100°C in different gas flow rates. The particle size of the powders was increased with increasing decomposition temperature, but it was decreased with increasing CO gas flow rate. The Fe powders produced at 500°C consisted of three layers of alpha-Fe/Fe_3C/amorphous phases, but it had two phase core-shell structure which consited of Fe_3C phase of core and graphite of shell at 1100°C.

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