• 한국전기전자재료학회논문지
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• 제37권1호
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• pp.63-67
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• 2024

In this study, we successfully synthesized copper oxide (Cu₂O) particles through a hydrothermal method at a relatively low temperature (150℃). The synthesis involved the precise control of molar concentrations of NaOH. Notably, Cu₂O particles were effectively synthesized when NaOH concentrations of 0.15 M and 0.20 M were utilized. While attempts were made at different molar concentrations, the synthesis of pure Cu₂O particles was only achieved at concentrations of 0.15 M and 0.20 M. In this experimental investigation, Cu₂O synthesized under these specific conditions exhibited absorption characteristics within the wavelength range of 640 to 570 nm, consistently exhibiting a band gap energy of 1.9 eV. These Cu₂O particles, characterized by their small band gap energy and straightforward synthetic method, hold significant promise for various applications including semiconductors and solar cells.

• 한국분말재료학회지
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• 제11권2호
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• pp.171-178
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• 2004

Effects of liquid phase and reinforcing particle morphology on the sintering of Al-6 wt％Cu-10 vol％ $Al_2O_3$ or SiC particles were studied in regards to densification, structure and transverse rupture properties. The Al-Cu liquid phase penetrated the boundaries between the aluminum matrix powders and the interfaces with reinforcing particles as well, indicating a good wettability to the powders. This enhanced the densification during sintering and the resulting strength and ductility. Since most of the copper added, however, was dissolved in the liquid phase and formed a brittle $CuAl_2$ phase upon cooling rather than alloyed with the aluminum matrix, the strengthening effect by the copper was not fully realized. Reinforcing particles of agglomerate type were found less suitable for the liquid phase sintering than solid type particles. $Al_2O_3$ and SiC particles protluced little difference on the sintering behavior but their size had a large effect. Repressing of the sintered composites increased density and bending properties but caused debonding at the matrix-particle interfaces and also fracturing of the particles.

• 열처리공학회지
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• 제7권2호
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• pp.96-102
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• 1994

The present work was aimed to examine the changes of the shape and particle size distribution(PSD) of ${\delta}^{\prime}$ particles on ageing in Al-Li-(Cu, Zr) alloys which had low density, high specific strength and stiffness, Increasing ageing time and temperature resulted in particles whose aspect ratio tended toward 1. The aspect ratio of ${\delta}^{\prime}$ particles was not dependent upon the ageing temperature and time in Al-Li-Cu alloy but was dependent upon them in Al-Li-Zr alloy. The PSD of ${\delta}^{\prime}$ particles in Al-Li-Zr alloy skewed to the right hand compared with that in Al-Li-Cu alloy, because $Al_3Zr$ phase in Al-Li-Zr alloy formed before ageing promoted the precipitation and growth of ${\delta}^{\prime}$ phase. Therefore, the PSD of the ${\delta}^{\prime}$ particles was found to be affected by the presence of $Al_3Zr$ particles. The growth rate of ${\delta}^{\prime}$ phase was not affected by the existence of the third transition phase $T_1$ formed by the addition of Cu in Al-Li alloy but was affected by the existence of $Al_3Zr$ formed by the addition of Zr in Al-Li alloy.

• 한국주조공학회지
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• 제16권6호
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• pp.556-564
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• 1996

Variation of shape and size of solid particles and solute redistribution in Mg-9wt.%Al, AI-4.5wt.% Cu, and AI-7wt.%Si alloys were investigated when they were heated to semi-solid temperatures and held without stirring. In the case of Mg-9wt.% Al and Al-4.5wt.%Cu alloys, the polygonal shaped solid particles were agglomerated with non-uniform distribution, and there were no disappearance of the solid/solid boundary until the end of melting. But in the case of an Al-7wt.%Si alloys, two or three spherical shaped particles were coalesced or separated individually, and the coalesced particles had no solid/solid interface on the contrary to the prevous case. The maximum size of solid particles during isothermal heating at high temperature was smaller than that at lower temperature, but the time required to reach the maximum size at high temperature was shorter than that at lower temperature. The concentrations of main solute atom whose distribution coefficient is lower than 1, decreased in the primary solid particles as the liquid fraction increased, and the gradient of solute concentration was steeper in Mg-9wt.%Al alloy and Al-4.5wt.%Cu alloy than that of Al-7wt.%Si alloy.

• 동력기계공학회지
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• 제14권4호
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• pp.50-55
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• 2010

In order to investigate tribological effects of nano copper particles impregnated(CuN) on surface polytetrafluoroethylene(PTFE) on sealing wear and an experimental study was carried out to determine the wear behavior of copper nano-particles impregnation two kind thickness in super critical $CO_2$ liquid. Experimental results showed that the friction coefficients of CuN PTFE at the low sliding speed(0.44m/s) and the oil temperature ($60^{\circ}C$) were higher than that of virgin PTFE. And a thin nano copper particles impreganated thickness was formed on the surface in the PTFE and the specimen with this treatment has much better friction properties than the original one. Fortunately, at the high load(80 N) and the oil temperature, the friction coefficient of CuN PTFE was lower than that of virgin PTFE. This evidenced the load carrying capacity of CuN PTFE was much better than that of virgin PTFE under the high load condition(80 N) specially. Therefore, it can be concluded that the friction coefficient variation of CuN PTFE is very small but its wear rate decreases greatly with increase in sliding speed.

• 마이크로전자및패키징학회지
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• 제23권3호
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• pp.51-56
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• 2016

내산화 특성을 가지는 구리(Cu) 기반의 미세 도전 필러를 제조하기 위하여 서브마이크론급의 은(Ag) 코팅 Cu 입자를 제조하고, 그 내산화 특성을 평가하였다. 평균 크기 $0.705{\mu}m$의 Cu 입자들을 습식 합성법으로 제작한 후, 에틸렌글리콜 용매를 사용한 연속 공정으로 Ag 도금을 실시하여 Ag 도금 Cu 입자를 제조하였다. Ag 도금 공정에서 제어한 주요 변수는 환원제 아스코빅산의 첨가 농도, Ag 전구체 용액의 주입속도 및 혼합 용액의 교반속도였는데, 이들의 변화에 따른 Ag 도금의 특성과 미세한 순수 은Ag 입자의 생성 변화를 관찰하였다. 그 결과 공정변수들을 최적화시킴으로써 불필요한 순수 Ag 입자들이 생성을 막고, Ag 도금 Cu 입자들간의 응집을 억제할 수 있었다. 최적 제조조건에서 제조된 Ag 도금 Cu 입자들은 다소간의 응집을 나타내었으나, 대기중에서 $10^{\circ}C/min$의 승온속도로 가열 시 약 $225^{\circ}C$에서야 0.1%의 무게 증가를 나타내었고, $150^{\circ}C$의 대기중에서는 75 분까지 무게 증가가 없는 우수한 내산화 특성을 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.

• 마이크로전자및패키징학회지
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• 제23권4호
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• pp.125-133
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• 2016

도전 페이스트의 필러로 사용되기 위한 미세 Cu 입자를 제조하기 위하여 아산화동 분말과 황산간의 고속 화학 반응을 이용한 증류수 기반의 습식 공정으로 Cu 입자의 합성을 실시하였다. $7^{\circ}C$에서 48%의 황산과 30 g의 $Cu_2O$를 사용한 조건에서 미반응 $Cu_2O$ 입자들이 제거되면서 입자들간의 응집이 개선된 순수 Cu 나노입자들이 제조되었다. 이후 최적 첨가제의 선택을 통하여 입자들간의 응집이 가장 억제된 224 nm 크기의 Cu 입자들을 제조할 수 있었다. 이러한 미세 Cu 입자 시료에서는 응집된 형태의 조대 입자들이 다소 존재하였고 입자들간의 연결부도 일부 관찰되었으나, 삼본밀을 사용한 레진 포물레이션과의 혼합 후에는 응집된 형태의 조대 입자들이 파괴되고 입자들간의 연결부들이 탈착되어 입자들의 응집이 풀리는 거동을 관찰할 수 있었다.

• 한국재료학회지
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• 제26권3호
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• pp.109-116
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• 2016

To achieve the fabrication of high-quality Ag-coated Cu particles through a wet chemical process, we reported herein pretreatment conditions using an ammonium-based mixed solvent for the removal of a $Cu_2O$ layer on Cu particles that were oxidized in air for 1 hr at $200^{\circ}C$ or for 3 days at room temperature. Furthermore, we discussed the results of post-Ag plating with respect to removal level of the oxide layer. X-ray diffraction results revealed that the removal rate of the oxide layer is directly proportional to the concentration of the pretreatment solvent. With the results of Auger electron spectroscopy using oxidized Cu plates, the concentrations required to completely remove 50-nm-thick and 2-nm-thick oxides within 5 min were determined to be X2.5 and X0.13. However, the optimal concentrations in an actual Ag plating process using Cu powder increased to X0.4 and X0.5, respectively, because the oxidation in powder may be accelerated and the complete removal of oxide should be tuned to the thickest oxide layer among all the particles. Back-scattered electron images showed the formation of pure fine Ag particles instead of a uniform and smooth Ag coating in the Ag plating performed after incomplete removal of the oxide layer, indicating that the remaining oxide layer obstructs heterogeneous nucleation and plating by reduced Ag atoms.

• 한국세라믹학회지
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• 제34권8호
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• pp.886-896
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• 1997

To investigate an effect of phase separation on precipitation characteristics of CuCl nanocrystals in CuCl doped nonlinear optical glasses, borosilicate glass systems with 9 different compositions with ~2wt% of CuCl were selected and CuCl doped glasses were prepared by melting and precipitation method. Microstructural properties of the CuCl doped glasses were analyzed by optical absorption spectroscopy, acid elution test, TEM, and EDXS. While phase separation did not occur in Glass A~D, interconnected and droplet microstructures due to phase separation were found in Glass E, F and Glass G~I, respectively. In the particular composition of the matrix glasses in this study, the precipitation of the CuCl particles was observed in the phase separable glasses, not in phase non-separable glasses. The CuCl particles were precipitated in both silica-rich phase region and boronrich phase region of the glass matrix. In the case of 7.7Na2O-36.6B2O3-52.7SiO2(mole%) glass, the larger CuCl particles than those in the silica-rich phase region were observed in the boron-rich phase region.