• 한국재료학회지
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• 제5권8호
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• pp.1005-1112
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• 1995

Al-Li-Cu-Mg합금에서 0~9% 범위의 stretching이 석출상 및 기계적성질에 미치는 영향을 조사하였다. Stretching을 하였을 경우 $\delta$'(A1$_3$Li)석출상의 크기는 변화가 없었으나 T$_1$(Al$_2$CuLi)석출상은 미세하고 균일하게 분포하였으며 입계석출물도 비교적 적게 형성되었다. 또한 변형부위에 분포하는 $\delta$'석출상에 의한 planar slip도 감소되었다. 항복강도는 15$0^{\circ}C$에서 120시간 시효처리 하였을때 stretching을 하지 않은 경우 328~342 Mpa에서 6% stretching을 하였을 경우 466~488MPa로 향상되었으며 연신율은 같은 조건에서 각각 9.7~10.4%와 5~5.7%를 나타내었다.

• 한국분말재료학회지
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• 제14권2호
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• pp.123-126
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• 2007

In this work, the dispersion behavior of $Y_2O_3$ particles in binary aluminum (Al)-copper (Cu) cast alloy was investigated with respect to Cu contents of 20 (hypoeutertic), 33 (eutectic) and 40 (hypereutectic) wt.%. In cases of hypo and hypereutectic compositions, SEM images revealed that the primary Al and ${\theta}$ phases were grown up at the beginning, respectively, and thereafter the eutectic phase was solidified. In addition, it was found that some of $Y_2O_3$ particles can be dispersed into the primary Al phase, but none of them are is observed inside the primary 6 phase. This different dispersion behavior of $Y_2O_3$ particles is probably due to the difference in the val- ues of specific gravity between $Y_2O_3$ particles and primary phases. At eutectic composition, $Y_2O_3$ particles were well dispersed in the matrix since there is few primary phases acting as an impediment site for particle dispersion during solidification. Based on the experimental results, it is concluded that $Y_2O_3$ particles are mostly dispersed into the eutectic phase in binary Al-Cu alloy system.

• 대한금속재료학회지
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• 제47권10호
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• pp.605-612
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• 2009

The suitability of twin roll strip casting for Ag-27.5%Cu-20.5%Zn-2.5%Mn-0.5%Ni brazing alloy (known as HS-49D) was examined in the present work and the mechanical properties and microstructure of the strip were also investigated. The effect of annealing heat treatment on the properties was also studied. The new manufacturing process has applications in the production of the brazing alloy. XRD and microstructural analyses of the Ag-27.5%Cu-20.5%Zn-2.5%Mn-0.5%Ni strip revealed a eutectic microstructure of an Ag-rich matrix (FCC) and a Cu-rich phase (FCC) regardless of heat treatment. The results of mechanical tests showed tensile strength of 434 MPa and 80% elongation for the twin roll casted strip. Tensile results showed decreasing strengths and increasing elongation with annealing heat treatment. Microstructural evolution and fractography were also investigated and related to the mechanical properties.

• 한국결정성장학회지
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• 제14권6호
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• pp.244-252
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• 2004

$CuISe_2$ 단결정 박막은 수평 전기로에서 합성한 $CuInSe_2$ 다결정을 증발원으로하여, hot wall epitaxy(HWE) 방법으로 증발원과 기판(반절연성-GaAs(100))의 온도를 각각 $620^{\circ}C$, $410^{\circ}C$로 고정하여 단결정 박막을 성장하였다. 이때 단결정 박막의 결정성은 광발광 스펙트럼과 이중결정 선 요동곡선(DCRC) 으로 부터 구하였다. Hall 효과는 van der Pauw 방법에 의해 측정되었으며, 293K에서 운반자 농도와 이동도는 각각 $9.62\times10^{16}/\textrm{cm}^3$, 296 $\textrm{cm}^2$/Vㆍs 였다. $CuAlSe_2$/Si(Semi-Insulated) GaAs(100) 단결정 박막의 광흡수와 광전류 spectra를 293k에서 10K까지 측정하였다. 광흡수 스펙트럼으로부터 band gap $E_g$(T)는 Varshni 공식에 따라 계산한 결과 1.1851 eV-($8.99\times10^{-4} eV/K)T^2$/(T+153k)였다. 광전류 스펙트럼으로 부터 Hamilton matrix(Hopfield quasicubic mode)법으로 계산한 결과 crystal field splitting Δcr값이 0.0087eV이며 spin-orbit Δso값은 0.2329 eV임을 확인하였다. 10K일 때 광전류 봉우리들은 n = 1일때 $A_1-, B_1$-와 $C_1$-exciton봉우리임을 알았다.

• 대한치과보철학회지
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• 제35권3호
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• pp.566-576
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• 1997

This study was performed to evaluate the tensile strength of solder joint in titanium and the wettability of 14K gold solder on titanium. Two pieces of titanium rod 30 mm in length and 3mm in diameter were butt-soldered with a 14K gold solder using the electric resistance heating under flux-argon atmosphere, the infrared heating under argon atmosphere, and the infrared heating under vacuum-argon atmosphere. A tensile test was performed at a crosshead speed of 0.5 mm/min, and fracture surfaces were examined by SEM. To evaluate the wettability of 14K gold solder on titanium, titanum plates of a $17{\times}17{\times}1mm$ were polished with #80-#2000 emery papers, and the spreading areas of solder 10 mg were measured by heating at 840 * for 60 seconds. The solder-matrix interface regions were etched by the solution of 10% KCN-10% (NH4)2S2O8, and analyzed by EPMA. The results obtained were summarized as follows ; 1. The maximum tensile strength was obtained when the titanium surface was polished with #2000 emery paper and soldered using the electric resistance heating under flux-argon atmosphere. Soldering strengths showed the significant difference between the electric resistance heating and the infrared heating(p<0.05). 3. The fracture surfaces showed the aspect of brittle fracture, and the failure developed along the interfaces of solder-matrix reaction zone. 4. The EPMA data for the solder-matrix interface region revealed that the diffusion of Au and Cu occurred to the titanium matrix, and the reaction zone showed the higher contents of Au, Cu and Ti than others.

• 마이크로전자및패키징학회지
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• 제22권1호
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• pp.15-19
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• 2015

본 연구에서는 OSP (organic solderability preservative) 표면처리된 PCB (printed circuit board) Cu 볼 패드의 변색을 검사하는 측정 시스템을 제안하였다. PCB 표면처리 중에서 OSP는 친환경적, 낮은 생산 비용 등의 장점으로 널리 이용되고 있으나 온도공정에 따른 변색이 발생하는 문제점이 있어서 접합 신뢰성 불량의 한 원인이 되고 있다. 이러한 변색 불량을 장치 비의존적 CIELAB 색좌표를 도입하여 분석하였다. 먼저, PCB 샘플을 검사하기 위해 적합한 측정 시스템을 표준 조명과 CCD 카메라를 이용하여 제작하고, 랩뷰 (labview) 프로그램을 이용하여 Cu 볼 패드의 변색을 검사하기 위한 이미지를 얻는 알고리즘을 제작하였다. 전체 PCB 이미지에서 이진화 (binarization) 및 외곽영역 추적 (edge detection) 영상처리 과정을 통하여 Cu 볼 패드만의 이미지를 획득하고, 장치 의존적인 RGB 색좌표에서 $3{\times}3$ 변환 행렬을 이용하여 CIELAB 색좌표로 변환하는 과정을 거친다. 본 측정 시스템을 이용하여 변색이 발생한 PCB 샘플을 분석한 결과 Cu 볼 패드 만의 이미지를 대상으로 분석하면 연산에 소요되는 시간이 감소하고 측정 시스템의 오인식률을 감소 시킬 수 있음을 실험적으로 증명하였다. 또한 CIELAB 색좌표 중 $L^*$ (밝음-어두움의 정도), $b^*$ (노랑-파랑의 정도)의 두 가지 기준의 조합이 Cu 볼 패드의 변색 검사에 적합한 색좌표로 분석되었다.

• 한국해양학회지
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• 제15권1호
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• pp.66-70
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• 1980

A method for the determination of dissolved species of Cd, Co, Cu, Ni, Pb and Zn in sea water by flame atomic absorption spectrophotometry (AAS) is described. Prior to analysis by AAS, these elements are concentrated by coprecipitation with iron pyrrolidinedithiocarbamate at pH 3 because of matrix effects and their low concentration levels in sea water. The detection limits are 0.01, 0.04, 0.02, 0.05, 0.08, and 0.03$\mu\textrm{g}$/l, and the relative standard deviations are 1.0, 2.4, 1.3, 2.9, 2.0 and 2.9% for Cd, Co, Cu, Ni, Pb and Zn, respectively. The method is shown to be satisfactory in terms of recovery and precision for the determination of these metals in sea water.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 C
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• pp.1651-1653
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• 1996

As electrode materials like as Cu-Pb, Cu-Bi, WC-Ag, W-Ag for vacuum circuit breaker have high chopping current or bad insulation-recovery characteristics, it can affect induction machinery like as transformer and motor. To produce low surge electrode material, it have been suggested Co-Ag-Se electrode which were infiltrated with Ag-Se intermetallic compound into sintered Co matrix. In this study, we would like to represent that production method and microstructure of Co-Ag-Se electrode material. The microstructure and characteristics of Ag-Se intermetallic compound and Co-(Ag-Se) electrode were investigated by using SEM, XRD, EPMA.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1996년도 춘계학술대회 논문집
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• pp.123-128
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• 1996

As electrode materials like as Cu-Pb, Cu-Bi, WC-Ag, W-Ag for vacuum circuit breaker have high chopping current or bad insulation-recovery characteristics, it can affect induction machinery like as transformer and motor. To produce low surge electrode material, it have been suggested Co-Ag-Te electrode which were infiltrated with Ag-Te intermetallic compound into sintered Co matrix in vacuum. In this paper, we would like to represent that production method and microstructure of Co-Ag-Te electrode material in each condition. The microstructure and characteristics of Ag-Te intermetallic compound and Co-(Ag-Te) electrode were investigated by using optical microscope, SEM, XRD, EPMA.

• 한국분말재료학회지
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• 제14권6호
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• pp.399-404
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• 2007

The Cu-based bulk metallic glass (BMG) composite was fabricated by spark plasma sintering (SPS) using of gas-atomized metallic glass powders and ductile brass powders. No defect such as pores and cavities was observed at the interface between the brass powder and the metallic glass matrix, suggesting that the SPS process caused a severe viscous flow of the metallic glass and brass phases in the supercooled liquid region, resulting in a full densification. The BMG composites shows some macroscopic plasticity after yielding, although the levels of strength decreased.