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급냉응고된 Al-(Fe , Ce) 합금에서 형성되는 석출상의 X-선적연구
박익민,이규한,최정철,조형호 ( Ik Min Park,Kyu Han Lee,Jeong Cheol Choe,Hyung Ho Jo ) 한국주조공학회 1988 한국주조공학회지 Vol.8 No.4
N/A To obtain detailed information on the metastable and the equilibrium phases in rapidly solidified Al-(Fe, Ce) alloys, analysis of X-ray diffraction pattern has been carried out. It has been found that the metastable phase formed in Al-Fe alloys including up to 6w% Fe is Al_6Fe and the equilibrium phase is Al₃Fe. Any X-ray diffraction peak corresponding to the equilibrium phase Al_(13)Fe₄has not been observed during aging. In Al-4wt% Fe alloy, which is ribbon shape with thickness less than 70㎛, aged at 400℃ for lh after rapid solidification, unidentified phase has been found. In Al-4wt% Ce alloy, only X-ray diffraction peak corresponding to the equilibrium phase, Al₄Ce has been observed. It has been found that the metastable phase Formed in Al-Fe-Ce alloys including up to 6wt% Fe and 4wt% Ce is Al_6Fe and the equilibrium phases are Al₃Fe and Al_(10)CeFe₂.
소실모형구조법에 의한 탄소강주강 제조시의 Carbon Pick-up 현상
박익민 ( Ik Min Park ),박희상 ( Hee Sang Park ),이동렬 ( Dong Ryol Lee ),이경환 ( Kyung Whoan Lee ),이진형 ( Zin Hyoung Lee ) 한국주조공학회 2003 한국주조공학회지 Vol.23 No.2
N/A It has been a major concern in the foundry that steel castings manufactured by the evaporative pattern casting process encounter the carbon pick-up problem. A carbon rich layer at the evaporative pattern cast surface is a result of interactions between the gaseous products from foamed polystyrene and the molten metal. The carburized layer with a high hardness makes it difficult to machine the casting. In this study, the influence of the density of EPS pattern and coatings on carbon pick-up phenomena of S25C and S45C commercial carbon cast steel were investigated. As the density of EPS pattern is increased, the carbon concentration of decomposed pattern is increased and the thickness of carburized layer at the surface of steel castings is increased. Also as the density of coatings is increased, the permeability of coatings is decreased and the thickness of carburized layer at the surface of steel castings is increased. S25C steel which has lower original carbon content compared to S45C steel exhibited severe carburization.
플라즈마 활성 소결에 있어서 다이스의 온도분포에 미치는 몰드 크기의 영향
이길근,박익민,Lee Gil-Geun,Park IK-Min 한국분말야금학회 2004 한국분말재료학회지 (KPMI) Vol.11 No.5
In the present study, the focus is on the analysis of the effect of the mold dimensions on the temperature distribution of a die during plasma activated sintering. The temperature distribution of a cylindrical mold with various dimensions was measured using K-type thermocouples. The temperature homogeneity of the die was studied based on the direction and dimensions of the die. A temperature gradient existed in the radial direction of the die during the plasma activated sintering. Also, the magnitude of the temperature gradient was increased with increasing sintering temperature. In the longitudinal direction, however, there was no temperature gradient. The temperature gradient of the die in the radial direction strongly depended on a ratio of die volume to punch area.
반응 용탕단조한 (Al2O3 SiO2+Ni) / Al 하이브리드 금속복합재료의 제조 및 특성
김상석,박익민,김성준,최일동 ( Sang Suk Kim,Ik Min Park,Sung Joon Kim,Il Dong Choi ) 한국주조공학회 1997 한국주조공학회지 Vol.17 No.4
N/A Mechanical properties of (10%Al₂O₃·SiO₂+5%Ni)/Al hybrid composites fabricated by the reaction squeeze casting were compared with those of (15%Al₂O₃·SiO₂)/Al composites. Al-Ni intertmetallic compounds (10-20㎛) formed by the reaction between nickel powder and molten aluminum were uniformly distributed in the Al matrix. These intermetallic compounds were identified as Al₃Ni using X-ray diffraction analysis and they resulted in beneficial effects on room and high temperature strength and wear resistance. Microhardness values of (10%Al₂O₃·SiO₂+5%Ni)/Al hybrid composite were greater by about 100Hv than those of (15%Al₂O₃·SiO₂)/Al composite. Wear resistance of (10%Al₂O₃·SiO₂+5%Ni)/Al hybrid composites was superior to that of (15%Al₂O₃·SiO₂)/Al composites regardless of the applied load. While tensile and yield strength of (10Al₂O₃·SiO₂+5%Ni)/Al hybrid composites were greater at room temperature and 300℃, strength drop at high temperature was much smaller in hybrid composites.
자동차 엔진부품용 Shaft에 플라즈마 산질화기술 적용
전은갑,박익민,이인섭,Jeon, Eun-Kab,Park, Ik-Min,Lee, In-Sup 한국재료학회 2006 한국재료학회지 Vol.16 No.11
Plasma nitrocarburising and plasma post oxidation were performed to improve the wear and corrosion resistance of S45C and SCM440 steel by a plasma ion nitriding system. Plasma nitrocarburizing was conducted for 3h at $570^{\circ}C$ in the nitrogen, hydrogen and methane atmosphere to produce the ${\varepsilon}-Fe_{2-3}$(N, C) phase. Plasma post oxidation was performed on the nitrocarburized samples with various oxygen/hydrogen ratio at constant temperature of $500^{\circ}C$ for 1 hour. The very thin magnetite ($Fe_3O_4$) layer $1-2{\mu}m$ in thickness on top of the $15{\sim}25{\mu}m$ ${\varepsilon}-Fe_{2-3}$(N, C) compound layer was obtained by plasma post oxidation. A salt spray test and electrochemical testing revealed that in the tested 5% NaCl solution, the corrosion characteristics of the nitrocarburized compound layer could be further improved by the application of the superficial magnetite layer. Throttle valve shafts were treated under optimum plasma processing conditions. Accelerated life time test results, using throttle body assembled with shaft treated by plasma nitrocarburising and post oxidation, showed that plasma nitrocarburizing and plasma post oxidation processes could be a viable technology in the very near future which can replace $Cr^{6+}$ plating.
조남정,박익민 ( Nam Jung Cho,Ik Min Park ) 한국주조공학회 1986 한국주조공학회지 Vol.6 No.3
The effect of pulverizing methods on sintered strength of degraphitized gray cast iron swarf was investigated. The main results are as follows: 1) The compressive fracture strength level of sintered cast iron powder is in the order of cutter mill powder, mortar grinding powder and ball mill powder; This is considered to be due to the increase in surface roughness. The increase in surface roughness factor leads to the increase in green strength and sintered strength. 2) The compressive fracture strength of sintered products which were compacted at 12t/㎠ and sintered at 1150℃ for 90min in the vacuum atmosphere, is higher than that of parent gray cast iron by the factor 2.5. 3) The increase in sintered strength is due to the spheroidal graphite precipitation at the finely dispersed round pore.