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기계적 합금화 공정에 의한 Fe가 코팅된 Mg 탈황 분말 제조 연구
송준우,천병선,홍순직,Song, Joon-Woo,Guillermo, Otaduy,Chun, Byong-Sun,Hong, Soon-Jik 한국분말야금학회 2012 한국분말재료학회지 (KPMI) Vol.19 No.3
In this research, the coating behavior of Mg and Fe desulfurization powder fabricated by low energy and conventional planetary mill equipment was investigated as a function of milling time, which produces uniform Fe coated powders due to milling energy. Since high energy ball milling results in breaking the Fe coated Mg powders into coarse particles, low energy ball milling was considered appropriate for this study, and can be implemented in desulfurization industry widely. XRD and FE-SEM analyses were carried out to investigate the microstructure and distribution of the coating material. The thickness of the Fe coating layer reaches a maximum of 14 ${\mu}m$ at 20 milling hours. The BCC structures of Fe particles are deformed due to the slip system of Fe coated Mg particles.
분말야금법으로 제조된 FeSi<sub>2</sub> 열전특성 화합물의 열처리 시간에 따른 미세조직과 상변화
박경태,신진교,홍순직,천병선,Park, Kyoung-Tae,Shin, Jin-Gyo,Hong, Soon-Jik,Chun, Byong-Sun 한국분말야금학회 2010 한국분말재료학회지 (KPMI) Vol.17 No.6
In this study, $FeSi_2$ as high temperature performance capable thermoelectric materials was manufactured by powder metallurgy.The as-casted Fe-Si alloy was annealed for homogenization below $1200^{\circ}C$ for 3 h. Due to its high brittleness, the cast alloy transformed to fine powders by ball-milling, followed by subsequent compaction (hydraulic pressure; 2 GPa) and sintering ($1200^{\circ}C$, 12 h). In order to precipitate ${\beta}-FeSi_2$, heat treatment was performed at $850^{\circ}C$ with varying dwell time (7, 15 and 55 h). As a result of this experiment thermoelectric phase ${\beta}-FeSi_2$ was quickly transformed by powder metallurgical process. There was not much change in powder factor between 7h and 55h specimens.
급속응고 6061Al/Graphite 복합재료의 볼밀링 시간에 따른 흑연 분산거동 및 기계적 특성
손현택,이재설,홍순직,천병선,Son, Hyeon-Taek,Lee, Jae-Seol,Hong, Soon-Jik,Chun, Byong-Sun 한국분말야금학회 2009 한국분말재료학회지 (KPMI) Vol.16 No.3
A composite of rapidly solidified Al-6061 alloy powder with graphite particle reinforcements was prepared by ball milling and subsequent hot extrusion. The microstructure and mechanical properties of these composites were investigated as a function of milling time. With increasing milling time, the gas atomized initially and spherical powders became elongated with a maximum aspect ratio after milling for 30 h. Then, refinement and spheroidization were achieved by further milling to 70 h with a homogeneous and fine dispersion of graphite particles forming between the matrix alloy layers. The best compression and wear properties were obtained in the powder milled for 70 h, associated with the increased fine and homogeneous distribution of graphite particles in the aluminum alloy matrix.
가스분무공정을 이용한 (AgSbTe<sub>2</sub>)<sub>15</sub>(GeTe)<sub>85</sub> 열전분말의 제조 및 특성평가
김효섭,이진규,구자명,천병선,홍순직,Kim, Hyo-Seob,Lee, Jin-Kyu,Koo, Jar-Myung,Chun, Byong-Sun,Hong, Soon-Jik 한국분말야금학회 2011 한국분말재료학회지 (KPMI) Vol.18 No.5
In this study, p-type $(AgSbTe_2)_{15}(GeTe)_{85}$: TAGS-85 compound powders were prepared by gas atomization process, and then their microstructures and mechanical properties were investigated. The fabricated powders were of spherical shape, had clean surface, and illustrated fine microstructure and homogeneous $AgSbTe_2$ + GeTe solid solution. Powder X-ray diffraction results revealed that the crystal structure of the TAGS-85 sample was single rhombohedral GeTe phase, which with a space group $R_{3m}$. The grain size of the powder particles increased while the micro Vickers hardness decreased with increasing annealing temperature within the range of 573 K and 723 K due to grain growth and loss of Te. In addition, the crystal structure of the powder went through a phase transformation from rhombohedral ($R_{3m}$) at low-temperature to cubic ($F_{m-3m}$) at high-temperature with increasing annealing temperature. The micro Vickers hardness of the as-atomized powder was around 165 Hv, while it decreased gradually to 130 Hv after annealing at 673K, which is still higher than most other fabrication processes.
기계적으로 밀링된 나노결정 Al-14wt%Ni-14wt%Mm 합금 분말의 열 안정성과 미세조직
홍순직,이윤석,천병선 대한금속재료학회 2003 대한금속·재료학회지 Vol.41 No.10
Mechanical milling has been performed for Al-14 wt%Ni-14 wt%Mm(Mm=misch metal) alloy powders rapidly solidified by the gas atomization method. The microstructure, hardness, and thermal stability of the powders were investigated as a function of milling time using X-ray diffraction(XRD), transmission electron microscopy(TEM), Vickers micro-hardness tester and differential scanning calorimetry(DSC) methods. In the early stage of milling, a cold-welded layer with a fine microstructure was formed along the edge of the milled powder (Zone A). The interior of the powder remained unworked (Zone B), resulting in a formation of two-zone microstructure. With increasing milling time, the nanocrystallite size decreased gradually reaching a size of about 10-15 nm and the lattice strain increased reaching a maximum value of about 0.7% after milling for 200 hours. The microhardness of the mechanically milled powder was 132 kg/㎟ after milling for 72 hours, and it increased to 290 kg/㎟ after milling for 200 hours because of the presence of fine nano structured phases.
Al/Graphite 합금 복합재료의 마모특성에 미치는 흑연의 영향
천병선,홍순직,김홍물 대한금속재료학회(대한금속학회) 2000 대한금속·재료학회지 Vol.38 No.7
In the present investigation, P/M method and extrusion process have been used to manufacture Al6061/graphite composite materials. The graphite particles were distributed uniformly within the Al6061 alloy matrix. The results showed that tensile properties and hardness of the composites reduced with increasing graphite volume and a comparison of experimental and calculated results was compatible to the tensile strength behavior. The wear behaviour of the 6061/graphite composites was also studied as a function of speed and distance with reference to different values of the matrix hardness. The obtained wear data were interpreted on the basis of the analysis of the surface and subsurface damage to the composites. As the hardness of the materials increased, their specific wear rate also decrease.
김택수,천병선,이홍로,김형섭,홍순직 대한금속재료학회(대한금속학회) 1998 대한금속·재료학회지 Vol.36 No.12
A bulky Al_(84)Ni_(9.5)Mm_(6.5) alloy has been produced by a high pressure gas atomization and warm compaction technique of the gas atomized powders smaller than 25㎛ in diameter, which has nanocrystalline Al particles embedded in amorphous matrix, at various compaction temperatures. The hardness, density, elongation and strength of the compacts have been examined and compared with the properties of heat treated specimens of melt spun ribbon with the same chemical Composition. The mechanical properties of the compacts are affected by the combined effects of the mechanical properties of the material itself, the porosity of the compacts and the bonding state between the powders. The hardness of the compacts is explained using the plasticity theory of porous materials.