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플라즈마 회전전극법에 의한 Al-Cu 합금 분말의 제조
최국선,김진영,이동희 연세대학교 대학원 1991 延世論叢 Vol.27 No.1
The production and characterization of Al-Cu alloy powders by the plasma- rotating-electrode process(PREP) was carried out to determine the influence of operating conditions(rotating speed, and plasma current) and alloy compositions on such particle characteristics as particle size distributon, shape, microstructure, and chemical composition. Each experimental condition showed a particle size range of 75∼353μm with mean sizes of 140∼160μm. The mean particle size of the powders changed with alloy compositions at the same rotating speed and plasma current. Particle shapes were mostly of the ligament type. Microstructures consisted mainly of dendrites, but also lamellar cell in the vicinity of eutectic composition. Al -20wt.% Cu powders of the same size, from even a single atomizing run, showed a wide variety of microstructure due to different thermal and nucleation history. Chemical compositions of alloy powders varied with particle size as a result of the interaction between high temperature plasma gas and material constituents of alloys during powder formation.
304L 오스테나이트 스테인레스강 분말의 소결성에 미치는 Mo의 첨가 영향
최국선,이동희,최왕규 연세대학교 산업기술연구소 1989 논문집 Vol.21 No.2
An investigation of Mo addition effect on the sinterability of 304L austenitic stainless steel powders was carried out by using the compacts of three different Mo contents(0.2 and 5 wt%) and using diffusion couple of same stainless steel and Mo powders. The compacts of pure stainless steel powder showed conventional sintering process. And also. we found the diffusion (alloying) layer, 60㎛, and porosity formation toward stainless steel compact in the vicinity of coupled zone by means of SEM and EDS analysis. The porosity of compacts to which Mo was added, was high compared with no Mo added compacts except early stage of sintering. But in compacts sintered at 1200℃ for 45 min, the abnormal increase of porosity could be understood by "bridging" effect of alloying layer formed during sintering process.
기계적 합금화에 의해 제조된 고규소 Al-Si 합금 나노 결정의 특성
이정일,김일호,홍태환,어순철,양계준,석현광,한만갑,최국선,김준수 대한금속재료학회 2003 대한금속·재료학회지 Vol.41 No.7
High silicon Al-Si alloys with nanocrystalline structures have been produced by mechanical alloying process. Microstructural changes of the Al-Si alloys were investigated by scanning electron microscopy and the transmission electron microscopy. X-ray diffraction analysis was also made to characterize the lattice constant, crystallite size and misfit strain. It was found that the effective milling time by attrition milling was about 12hours for Al-70 wt%Si alloy system. The Al and Si crystallites were reduced to about 30 nm and 70 nm, respectively, by the mechanical alloying for more than 12hours. The misfit strains increased with milling time UD to 240 hours, and saturated to 5.73×10^(-3) for Al and Si crystallites, respectively.
임재원,Good-Sun Choi,Dmitri Elanski,Kouji Mimura,Minoru Isshiki 한국자원공학회 2007 Geosystem engineering Vol.10 No.1
Recently, hydrogen plasma arc melting (HPAM) has been expected to be a practical melting and refining technique for metals and alloys. The effect of H2 addition to the Ar plasma gas on the purification of metals and alloys has been described by possible chemical reactions of impurities with activated hydrogen atoms on a molten metal as well as the increase in temperature of a metal surface. Trace impurity concentration of refined metals is determined using glow discharge mass spectrometry (GDMS). This method is used to determine trace elements quantitatively because GDMS is a direct solid-state analytical method that uses no chemical process and provides reliable quantitative concentrations for most elements below 0.01 ppm. We reviewed the refining effect of HPAM for several metals by trace impurity analysis using GDMS.