• 소성∙가공
• /
• 제15권2호
• /
• pp.143-147
• /
• 2006

Effect of processing condition on the hot extrusion of Al-Zn-Mg-Sc alloy was investigated. For this purpose, hot compression test and FE-simulation were conducted via Thermecmaster-Z and DEFORM-3D, respectively. The microstructure evolution during hot extrusion and post heat-treatment was investigated and deformation mechanisms were analyzed by constructing processing map. FE-simulation results show that the temperature difference between container and billet has considerable influence on the final shape of extruded T-shape bar. The relation between applied load and processing time was predicted by the FE-analysis as well as punch speed vs. stroke chart.

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 2005년도 추계학술대회 논문집
• /
• pp.202-205
• /
• 2005

Effect of processing condition on the hot extrusion of Al-Zn-Mg-Sc alloy was investigated. For this purpose, hot compression test and FE-simulation were conducted via Thermecmasteer-Z and DEFORM-3D, respectively. The microstructure evolution during hot extrusion and post heat-treatment was investigated and deformation mechanisms were analyzed by constructing processing map. FE-simulation results show that the temperature difference between container and billet has considerable influence on the final shape of extruded T-shape bar. The relation between applied load and processing time was predicted by the FE-analysis as well as punch speed vs. stroke chart.

• 한국주조공학회지
• /
• 제32권4호
• /
• pp.181-189
• /
• 2012

The microstructures of self-designed 7000 series Aluminium alloys added with Sc are observed. Moreover, the mechanical properties of the Sc-added Aluminium alloys are evaluated as a function of tensile temperature to establish the conditions of a following extrusion process. New casting conditions in the aluminium alloys added with Sc could be established by changing the casting speed and stirring time in the existing casting conditions of Aluminium alloys. The Sc addition results in $Al_3(Sc,Zr)$ precipitates in the cast alloys, and leads to the formation of equal-axed grains and fine grains. After homogenization heat treatment at $450^{\circ}C$, the Sc-added Aluminium alloys showed the highest elongation values in the temperature ranging from $300{\sim}400^{\circ}C$.

• 한국재료학회지
• /
• 제13권12호
• /
• pp.819-824
• /
• 2003

The Al-7.7Zn-2.0Mg-1.9Cu-0.1Zr-0.1Sc alloy exhibited excellent elongation by the new thermomechanical treatment (TMT) process; solution treatment and furnace cooling\longrightarrowhot and cold rolling and then annealing for short time. Tensile test at high temperature from 430 to $500^{\circ}C$ has been performed with various strain rates using for the Al-7.7Zn-2.0Mg-1.9Cu-0.1Zr-0.1Sc alloy obtained by the TMT process. The elongation of the Al-7.7Zn-2.0Mg-1.9Cu-0.1Zr-0.1Sc was 550% tensile tested at $470^{\circ}C$ temperature and 2.2 $\times$ $10^{-3}$ $s^{-1}$ strain rate. The m value of Al-7.7Zn-2.0Mg-1.9Cu-0.1Zr-0.1Sc alloy deformed 85% increased from 0.33 to 0.46 with increasing total elongation. This new TMT process was very simple and easy to make the sheets in the company.

• 한국지구과학회지
• /
• 제29권4호
• /
• pp.328-340
• /
• 2008

제주도 서부해역에 분포하는 퇴적물의 기원지를 밝히기 위해 이곳 표층퇴적물의 지화학적 조성을 분석하였으며, 그 결과를 중국의 황하와 양자강 그리고 한국의 강 퇴적물과 비교 연구하였다. 연구지역 퇴적물의 평균입도는 $3.6{\sim}8.5{\phi}$ 범위의 조립질실트 퇴적상으로 구성되며 탄산염 함량은 $0.92{\sim}9.75%$(평균 3.65%)범위를 갖는다. 총유기탄소와 총질소(TN)의 비율(평균 9.4)에서 연구지역의 유기물은 육성 기원보다 해양성 기원이 상대적으로 우세하였다. 주성분 원소들의 공간분포에서 Fe/Al, Mn/Al, Ti/Al의 함량비는 양자강 하구역과 가까운 남서쪽 지역에서 높은 농도를 보여 양자 기원 물질이 연구지역으로 유입되고 있음을 추론케한다. 연구지역 퇴적물의 Sc/Al 대 Cr/Th, Th/Sc 대 Nb/co, Ti/Nb 대 Th/Sc의 지화학적 구분지수는 황하와 양자강가원 퇴적물을 구분해 주는 유용한 지화학적 지시자로 제시될 수 있었다. 연구지역의 서쪽에 분포하는 대부분의 퇴적물은 황하기원 퇴적물과 유사한 특징을 보였고 양자강 하구역과 가까운 남서쪽 지역의 퇴적물은 양자강기원 퇴적물과 유사성을 보였으며, 북동쪽 지역에 분포하는 퇴적물 시료는 다른 지역 퇴적물 보다 높은 비 값을 보여, 따라서 제주도 서부해역은 복합기원 퇴적물이 집적되고 있음을 의미한다.

• 한국주조공학회지
• /
• 제35권6호
• /
• pp.147-154
• /
• 2015

The effects of Sc and Sr elements on the modification of the eutectic $Mg_2Si$ phase and the castability were investigated in the Al-4wt%Mg-0.9wt%Si-0.3wt%Mn-0.15wt%Fe alloy. Measurements of the cooling curve and microstructure observations were performed to analyze the additional effects of Sc and Sr minor elements during the solidification process. A prominent effect found on the modification of the eutectic $Mg_2Si$ phase with additions of the Sr and Sc elements. Here, a fine eutectic $Mg_2Si$ phase and a decrease in the growth temperature of the eutectic $Mg_2Si$ phase were evident with an addition of Sc element up to 0.2 wt%. The growth temperature of the eutectic $Mg_2Si$ phase decreased and the effect on the modification of the eutectic $Mg_2Si$ phase increased with the addition of Sr element up to 0.02 wt%. The addition of 0.02wt%Sr had the strongest effect on the modification of the eutectic $Mg_2Si$ phase, and the resulting microstructure of the eutectic $Mg_2Si$ phase was found to have a fibrous morphology with a decreased aspect ratio and an increased modification ratio. Fluidity and shrinkage tests were conducted to evaluate the castability of the alloy. The addition of 0.02wt%Sr effectively increased the fluidity of the alloy, while an addition of Sc did not show any effect compared to when nothing was added. The maximum filling length was recorded for 0.01wt%TiB-0.02wt%Sr owing to the effect of the fine ${\alpha}$-Al grains. The macro-shrinkage ratio decreased, while the micro-shrinkage ratio increased with the addition of various eutectic modifiers. The highest ratio of micro-shrinkage was recorded for the 0.02wt%Sr condition. However, the total shrinkage ratio was nearly identical regardless of the amounts added in this study.

• 한국결정학회지
• /
• 제10권1호
• /
• pp.83-87
• /
• 1999

부유대용융법에 의하여 전이금속, 희토류금속, 및 3A족 금속이온의 종류와 농도를 조절하면서 Rutile 단결정을 성장하였으며, 결정결함과 1.55 ㎛에서의 광 투과도에 미치는 각 불순이온의 영향을 조사하였다. 주입된 불순이온 중에서 양호한 결정형을 나타내는 이온은 V5+, Fe3+, Al3+, Zr4+, Ga3+, Sc3+이었으며, Al3+, Zr4+, Sc3+ 이온은 우수한 투과도를 나타내었다. 성장된 결정 중에서 가장 양호한 결정형을 제공하고, 산소결핍 및 low-angle grain boundaries의 형성을 최대로 억제하며, 양호한 투과도를 나타낸 우수한 품질의 Rutile 단결정은 TiO2 99.4 at%-Al2O3 0.6 at%로 평가되었다.

• EDISON SW 활용 경진대회 논문집
• /
• 제5회(2016년)
• /
• pp.333-335
• /
• 2016

본 연구에서는 제 1원리 계산을 기반으로 대표적인 p-type TCO 중 하나인 Cu-based delafossite ($CuMO_2$, M=Al, Ga, In, Sc, Y) 의 band structure 및 그에 따른 경향성을 분석하였다. 그 결과, 13족에 속하는 M (Al, Ga, In)은 valence band maximum (VBM)에서 2개의 flat한 line이 나타났고, 3족에 속하는 M (Sc, Y)는 Z point에서도 VBM과 비슷한 값이 나타났다.

• Bulletin of the Korean Chemical Society
• /
• 제19권1호
• /
• pp.63-67
• /
• 1998

The synthesis and characterization of the monomeric group 13 heterocyclic thiosemicarbazone complexes $Me_2M[SC_4H_3CHNNC(S)SCH_3]$ (M=Al (2), Ga (3)) are described. Compounds 2-3 were prepared using $MMe_3$ (M=Al, Ga) in toluene with 2-thiophenecarboxaldehyde-S-methyldithiocarbazat e under anaerobic conditions. These complexes have been characterized by $^1H\;NMR,\; ^{13}C\; NMR$, elemental analyses, and single-crystal X-ray diffraction. 2 crystallizes in the monoclinic space group $P2_1/c$ with unit cell parameters a=10.2930(5) Å, b=18.564 (1) Å, c=7.3812(6) Å, V=1347.9(2) Å3, $D_{calc}=1.342\; gcm^{-3}$ for Z=4, 9281 reflections with $I_o<3{\sigma}\;(I_o),$ R1=0.0500 and wR2=0.0526. 3 crystalizes in the orthorhombic space group $P_{bca}$ with unit cell parameters a=13.340(3) Å, b=19.9070(5) Å, c=11.3690(2) Å, $V=2673.88(9)\;{\AA}^3$, $D_{calc}=1.511\; gcm^{-3}$ for Z=8, 17004 reflections with $I_o>3{\sigma}\;(I_o),$, R1=0.0480 and wR2=0.0524. Compound 3 is a monomeric gallium compound with a weak interaction between the pendant thiophene and the gallium center.

• ETRI Journal
• /
• 제27권3호
• /
• pp.319-325
• /
• 2005

In this paper the effect of temperature on the electrical properties of organic semiconductor disperse orange dye 25 (OD) have been examined. Thin films of OD have been deposited on $In_{2}O_{3}$ substrates using a centrifugal machine. DC current-voltage (I-V) characteristics of the fabricated devices $(Al/OD/In_{2}O_{3)$ have been evaluated at varying temperatures ranging from 40 to $60^{\circ}C$. A rectification behavior in these devices has been observed such that the rectifying ratio increases as a function of temperature. I-V characteristics observed in $Al/OD/In_{2}O_{3)$ devices have been classified as low temperature $({\leq} 50^{\circ}C)$ and high temperature characteristics (approximately $60^{\circ}C$). Low temperature characteristics have been explained on the basis of the charge transport mechanism associated with free carriers available in OD, whereas high temperature characteristics have been explained on the basis of the trapped space-charge-limited current. Different electrical parameters such as traps factor, free carrier density, trapped carrier density, trap density of states, and effective mobility have been determined from the observed temperature dependent I-V characteristics. It has been shown that the traps factor, effective mobility, and free carrier density increase with increasing values of temperature, whilst no significant change has been observed in the trap density of states.