• Journal of the Microelectronics and Packaging Society
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• v.23 no.4
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• pp.125-133
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• 2016

With the aim of using a filler material in a conductive paste, fine Cu nanoparticles were synthesized through the high-speed chemical reaction between cuprous oxide ($Cu_2O$) powder and sulfuric acid in distilled water. Under external temperature of $7^{\circ}C$, sulfuric acid concentration of 48%, and $Cu_2O$ amount of 30 g, the $Cu_2O$ particles were eliminated and slightly aggregated Cu nanoparticles were synthesized. Futhermore, Cu nanoparticles of 224 nm, in which the aggregation between particles was obviousiy much suppressed, were synthesized with the choice of an additive. In the particle sample, occasionally there are coarse particles formed by the aggregation of fine nanoparticles and weak linkages between the nanoparticles. However, the coarse particles were destroyed and the linkages were broken after mixing with a resin formulation, indicating the behavior of untangling the aggregation between nanoparticles.

• Journal of the Korean Ceramic Society
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• v.56 no.4
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• pp.387-393
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• 2019

A N₂H₄-Cu(I)-HNO₃ solution was used to dissolve magnetite powders and a simulated oxide film on Inconel 600. The addition of Cu(I) ions to N₂H₄-HNO₃ increased the dissolution rate of magnetite, and the reaction rate was found to depend on the solution pH, temperature, and [N₂H₄]. The dissolution of magnetite in the N₂H₄-Cu(I)-HNO₃ solution followed the contracting core law. This suggests that the complexes of [Cu⁺(N₂H₄)] formed in the solution increased the dissolution rate. The dissolution reaction is explained by the complex formation, adsorption of the complexes onto the surface ferric ions of magnetite, and the effective electron transfer from the complexes to ferric ions. The oxide film formed on Inconel 600 is satisfactorily dissolved through the successive iteration of oxidation and reductive dissolution steps.

• Journal of the Korean institute of surface engineering
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• v.5 no.3
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• pp.77-85
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• 1972

A method of preparation of synthetic ignorgaic coating on copper (patina) has been presented . An Eh--pH diagram was constructed for the present Cu-H2O-SO$_4$ system using the most recently available thermodynamic data. In the path of the patination at room temperature the general behaviour of copper in acidic copper sulfate solutions with potassium chlorate as an oxidizing agent appeared to follow those predictable in this Eh-pH diagram. In the presence 0.05 molar cupric sulfate at a temperature of about 28$^{\circ}C$ a green brochantite (CuSO$_4$$.$3Cu(OH)$_2$) layer was formed on copper sheet in 20 days. In a solution having an initial pH of 3.5 the development of a brochantite coating has been observed to take place in two stages. In the first, a layer of cuprous oxide formed on the copper at a relatively rapid rate. In the ensuing step the outer layer of cuptrite was oxidized at much slower rate to form brochantite. The syntetic coatings appeared to consist of crystal-lites of brochanitite growing perpendicular to the cuprose oxide surface. The outer tips of the -crystallites were reasily broken off and gave to the layer a rather chalky character. Underneath, at the brochantite Cu$_2$O interface, however, the green layers were firmely attached. The effect of reagent concentration , solution agitation , and moderate temperature increase were investigated to improve the quality of coating. So also in a qualitative way were the effect of light.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.220-220
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• 2003

최근, Cu기판 위에 YBaCuO$_{7-x}$ 초전도체를 입혀 초전도 선재를 제작하려는 연구가 이루어지고 있으며 이 과정에서 CuO와 Cu$_2$O가 생성된다는 보고가 있다. CuO 및 Cu$_2$O의 생성은 초전도 선재의 전기전도적 특성 및 기계적 특성에 상당한 영향을 끼칠 수 있다. 따라서 CuO와 Cu$_2$O에 대한 연구가 필요하다고 할 수 있다. 본 연구에서는 DV-X$\alpha$ 분자궤도법을 통해 CuO와 Cu$_2$O에 대한 (Cu$_{29}$ O$_{58}$ )$^{58-}$ , (Cu$_{52}$ O$_{19}$ )$^{14+}$ 모델을 이용하여 전자상태계산을 하였다. CuO, Cu$_2$O의 valence orbital level 구조 및 DOS (Density of State)를 통해 Cu원자와 O원자간의 공유결합 세기를 측정하였으며 CuO, Cu$_2$O 서로간의 차이점을 분석하였다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.4
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• pp.425-429
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• 2009

The protection for copper tarnish was developed by surface treatment method and volatile corrosion inhibiting (VCI) technology. The performance of surface treatment and VCI material is also examined in simulated test environment. Benzotriazole (BTAH) solution that contained molybdate showed best performance than others. Usage of VCI materials with surface treatment was more effective. The protection film foamed on the surface of copper was investigated by auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS). Molybdate does not participate in the formation of the protective film but promotes the passivation effect. This facilitates the stabilization of the cuprous oxide film, and strengthens the adsorption of BTAH.

• Journal of the Korean Chemical Society
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• v.16 no.2
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• pp.74-79
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• 1972

The semiconductivity of polycrystalline $Cu_2O$ has been studied between $220^{\circ}C$ and $680^{\circ}C under partial pressures of oxygen from $4.06{\times}10^{-3}\;to\;10^{-5 }\;mmHg$. The plots of log conductivity vs 1/T at constant oxygen pressure were found to be linear, and the activation energies obtained from the slopes of these plots above the first transition point showed that the energies were greater under high oxygen pressure than under low pressure. The transition points between the stable range and the unstable range of $Cu_2O$ were found from the curves. The dependence of the semiconductivity on the $O_2$ pressure, in the above temperature range, is shown hysteresis.

• Molecules and Cells
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• v.39 no.3
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• pp.195-203
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• 2016

Copper is an essential element required for a variety of functions exerted by cuproproteins. An alteration of the copper level is associated with multiple pathological conditions including chronic ischemia, atherosclerosis and cancers. Therefore, copper homeostasis, maintained by a combination of two copper ions ($Cu^+$ and $Cu^{2+}$), is critical for health. However, less is known about which of the two copper ions is more toxic or functional in endothelial cells. Cubic-shaped $Cu_2O$ and CuO crystals were prepared to test the role of the two different ions, $Cu^+$ and $Cu^{2+}$, respectively. The $Cu_2O$ crystal was found to have an effect on cell death in endothelial cells whereas CuO had no effect. The $Cu_2O$ crystals appeared to induce p62 degradation, LC3 processing and an elevation of LC3 puncta, important processes for autophagy, but had no effect on apoptosis and necrosis. $Cu_2O$ crystals promote endothelial cell death via autophagy, elevate the level of reactive oxygen species such as superoxide and nitric oxide, and subsequently activate AMP-activated protein kinase (AMPK) through superoxide rather than nitric oxide. Consistently, the AMPK inhibitor Compound C was found to inhibit $Cu_2O$-induced AMPK activation, p62 degradation, and LC3 processing. This study provides insight on the pathophysiologic function of $Cu^+$ ions in the vascular system, where $Cu^+$ induces autophagy while $Cu^{2+}$ has no detected effect.

• Applied Chemistry for Engineering
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• v.2 no.3
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• pp.289-299
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• 1991

In order to obtain glasses appropriate to the thick film copper conductors, nine glasses based on both lead borosilicate and leadless borosilicate systems were made and the applicabilities of them were examined in conjunction with the requirements for thick film copper conductors. As the results, it was found that all the glasses are fitted to provide suitable sheet resistance, solderability and solder leach resistance to thick film copper conductors. However, it was turned out that only the lead borosilicate based glasses worked for getting usable aged adhesion strength of copper thick film to the alumina substrate, while copper conductor films made from the other glasses had poor aged adhesion strengths. Particularly cuprous oxide added lead borosilicate glass was considered as one of the most favorable glasses for manufacturing thick film copper conductors.

• Journal of the Korean Society of Safety
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• v.19 no.2
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• pp.1-5
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• 2004

Al-brass is the raw material of mnufacturing tubes for heat exchanger of vessel where seawater is used to coolant because it has high level of heat coductivity and excellent mechanical properties and high level of corrosion resistance due to cuprous oxide($Cu_2O$) layer against seawater. However, damage of Al-brass tubes for heat exchanger of vessel is reported that local corrosion such as stress corrosion cracking occurred by synergism effect between mechanical factor and corrosion environment. In this study, to investigate on the effect of stress on the polarization characteristics of Al-brass. At the stress of 0% and 95% yield strength by constant displacement tester, in 3.5% NaCl + 0.1% $NH_4OH$ solution, the polarization tests were carried out. And thus open circuit potential, corrosion current density, anodic polarization, cyclic polarization and dezincification behavior of Al-brass are investigated.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.39 no.4
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• pp.291-297
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• 2003

Al-brass is usually used as the tube material of vessel's heat exchanger for seawater cooling system because it has high thermal conductivity and good mechanical properties and high corrosion resistance due to cuprous oxide (Cu20) layer against seawater. However, Al-brass tubes of heat exchanger for vessel at the actual environment is reported that local corrosion such as stress corrosion cracking occurred by synergism effect between mechanical factor and corrosion environment In this paper, the effect of corrosion environment on the stress corrosion cracking of Al-brass in various NH4OH of 3.5% NaCl solution, under flow by constant displacement tester. Based on the test results, the behavior of polarization, stress corrosion crack propagation and dezincification phenomenon of Al-brass are investigated. The main results are as follows：(1) Increasing range of potential from open circuit potential to repassivation gets lower, as the contain rate of NH4OH gets higher. (2) As contain rate of NH4OH gets higher, SCC of Al-brass is become activation but the protection film(Cu20) of Al-brass is created in 3.5% NaCl solution. (3) According as content of NH4OH increases in 3.5% NaCl solution, the dezincifiction area is spread. It is concluded that dezincification occurred by localized preferential anodic dissolution at stress focusing region.