• Elastomers and Composites
• /
• v.56 no.3
• /
• pp.113-116
• /
• 2021

In this study, we report a facile fabrication of multi-walled carbon nanotubes (MWCNTs)-CuO composites synthesized by a microwave method using MWCNTs and copper oxide (CuO). The number of copper hydrate precursors affect the size and number of CuO domains formed along the MWCNTs in the composites. The domain size is controllable from 239 nm to 348 nm. The composites are characterized by transmission electron microscopy, energy dispersive spectrometry, X-ray diffraction (XRD), Raman spectroscopy, and UV-Vis spectroscopy. The CuO produced in the composites is confirmed to be tenorite with a monoclinic crystal structure through the XRD patterns of (-111), (111) and (-202).

• Proceedings of the Materials Research Society of Korea Conference
• /
• 2010.05a
• /
• pp.49.2-49.2
• /
• 2010

Copper oxide films have been deposited on silicon substrates by direct current magnetron sputtering of Cu in O2 / Ar gas mixtures. The target oxidation occurring as a result of either adsorption or ion-plating of reactive gases to the target has a direct effect on the discharge current and the resulting composition of the deposited films. The kinetic model which relates the target oxidation to the discharge current was proposed, showing the one-to-one relationship between discharge current characteristics and film stoichiometry of the deposited films.

• Journal of Korean Society of Environmental Engineers
• /
• v.28 no.3
• /
• pp.249-256
• /
• 2006

Catalytic combustion of toluene was investigated on the Cu-Mn oxide catalysts prepared by the impregnation(Imp) and the deposition-precipitation(DP) methods. The mixing of copper and manganese has been found to enhance the activity of catalysts. It is then found that catalytic efficiency of the Cu-Mn oxide catalyst prepared by the DP method on combustion of toluene is much higher than that of the Cu-Mn oxide catalyst prepared by Imp method with the same chemical composition. The catalyst prepared by the deposition-precipitation method observed no change of toluene conversion at time on stream during 10 days and at the addition of water vapor. On the basis of catalyst characterization data, it has been suggested that the catalysts prepared by the DP method showed uniform distribution and smaller particle size on the surface of catalyst and then enhanced reduction capability of catalysts. Therefore, we think that the DP method leads on progressive capacity of catalyst and promotes stability of catalyst. It was also presumed that catalytic conversion of toluene on the Cu-Mn oxide catalyst depends on redox reaction and $Cu_{1.5}Mn_{1.5}O_4$ spinel phase acts as the major active sites of catalyst.

• Journal of the Korean institute of surface engineering
• /
• v.32 no.6
• /
• pp.647-657
• /
• 1999

Due to the inherently poor adhesion strength of Cu-based leadframe/EMC (Epoxy Molding Compound) interface, popcorn cracking of thin plastic packages frequently occurs during the solder reflow process. In the present work, in order to enhance the adhesion strength of Cu-based leadframe/EMC interface, black-oxide layer was formed on the leadframe surface by chemical oxidation of leadframe, and then oxidized leadframe sheets were molded with EMC and machined to form SDCB (Sandwiched Double-Cantilever Beam) and SBN (Sandwiched Brazil-Nut) specimens. SDCB and SBN specimens were designed to measure the adhesion strength between leadframe and EMC in terms of critical energy-release rate under quasi-Mode I ($G_{IC}$ ) and mixed Mode loading ($G_{C}$ /) conditions, respectively. Results showed that black-oxide treatment of Cu-based leadframe initially introduced pebble-like X$C_2$O crystals with smooth facets on its surface, and after the full growth of $Cu_2$O layer, acicular CuO crystals were formed atop of the $Cu_2$O layer. According to the result of SDCB test, $Cu_2$O crystals on the leadframe surface did not increase ($G_{IC}$), however, acicular CuO crystals on the $Cu_2$O layer enhanced $G_{IC}$ considerably. The main reason for the adhesion improvement seems to be associated with the adhesion of CuO to EMC by mechanical interlocking mechanism. On the other hand, as the Mode II component increased, $G_{C}$ was increased, and when the phase angle was -34$^{\circ}$, crack Kinking into EMC was occured.d.

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

• Korean Journal of Metals and Materials
• /
• v.48 no.8
• /
• pp.749-756
• /
• 2010

Low carbon steels were oxidized isothermally at 1050 and $1180^{\circ}C$ for 4 hr in air in order to determine the effect of alloying elements Si, S, Cu, Sn, and Ni on oxidation. For oxidation resistance of low carbon steels, the beneficial elements were Si, Cu, and Ni, whereas the harmful elements were S and Sn. The most active alloying element, Si, was scattered inside the oxide scale, at the scale-alloy interface, and as an internal oxide precipitate. The relatively noble elements such as Cu and Ni tended to weakly segregate at the scale-alloy interface. Sulfur and Sn were weakly, uniformly distributed inside the oxide scale. Excessively thick, non-adherent scales containing interconnected pores formed at $1180^{\circ}C$.

• Journal of Powder Materials
• /
• v.30 no.4
• /
• pp.332-338
• /
• 2023

Thermite welding is an exceptional process that does not require additional energy supplies, resulting in welded joints that exhibit mechanical properties and conductivity equivalent to those of the parent materials. The global adoption of thermite welding is growing across various industries. However, in Korea, limited research is being conducted on the core technology of thermite welding. Currently, domestic production of thermite powder in Korea involves recycling copper oxide (CuO). Unfortunately, controlling the particle size of waste CuO poses challenges, leading to the unwanted formation of pores and cracks during thermite welding. In this study, we investigate the influence of powder particle size on thermite welding in the production of Cu-thermite powder using waste CuO. We conduct the ball milling process for 0.5-24 h using recycled CuO. The evolution of the powder shape and size is analyzed using particle size analysis and scanning electron microscopy (SEM). Furthermore, we examine the thermal reaction characteristics through differential scanning calorimetry. Additionally, the microstructures of the welded samples are observed using optical microscopy and SEM to evaluate the impact of powder particle size on weldability. Lastly, hardness measurements are performed to assess the strengths of the welded materials.

• Journal of Powder Materials
• /
• v.10 no.6
• /
• pp.422-429
• /
• 2003

The reduction mechanism of the composite powders mixed with $WO_3$ and CuO has been studied by using thermogravimetry (TG), X-ray diffraction, and microstructure analyses. The composite powders were made by simple Turbula mixing, spray drying, and ball-milling in a stainless steel jar with the ball to powder ratio of 32 to 1 at 80 rpm for 1 h without process controlling agents. It is observed that all the oxide composite powders are converted to W-coated Cu composite powder after reducing treatment under hydrogen atmosphere. For the formation mechanism of W-coated Cu composite powder, the sequential reduction steps are proposed as follows: CuO contained in the ball-milled composite powder is initially reduced to Cu at the temperature range from 20$0^{\circ}C$ to 30$0^{\circ}C$. Then, $WO_3$ powder is reduced to W $O_2$ via W $O_{2.9}$ and W $O_{2.72}$ at higher temperature region. Finally, the gaseous phase of $WO_3(OH)_2$ formed by reaction of $WO_2$ with water vapour migrates to previously reduced Cu and deposits on it as W reduced by hydrogen. The proposed mechanism has been proved through the model experiment which was performed by using Cu plate and $WO_3$ powder.

• Journal of the Korean Ceramic Society
• /
• v.38 no.11
• /
• pp.1000-1007
• /
• 2001

In an evacuated tube solar collector, the stable sealing of the heat pipe to the glass tube is important for the collector to use for a long period of time. The sealing of copper tube to the glass is quite difficult because of the large differences in the physical and chemical properties of the two materials. In this study, therefore, a proper copper oxide layer was induced to improve the chemical bonding of the two materials, and the oxidation state of copper and the interface between copper and glass were examined by XRD, SEM and EDS. Its bonding strength was also measured. Cu$_2$O was formed when the bare copper was heat-treated under 600$^{\circ}C$, while CuO oxide layer was formed above that temperature. The bonding state of CuO to the copper was very poor. The borate treatment of the copper, however, extend the stable forming of Cu$_2$O layer to 800$^{\circ}C$. Borosilicate glass tube was sealed to a copper tube by Housekeeper method only when the sealing part was covered with Cu$_2$O layer. The bonding strength at the interface was measured 354.4N, its thermal shock resistance was acceptable.

• Journal of the Microelectronics and Packaging Society
• /
• v.24 no.2
• /
• pp.37-41
• /
• 2017

Cuprous oxide ($Cu_2O$) is one of the potential candidates as an absorber layer in ultra-low-cost solar cells. $Cu_2O$ is highly desirable semiconducting oxide material for use in solar energy conversion due to its direct band gap ($E_g={\sim}2.1eV$) and high absorption coefficient that absorbs visible light of wavelength up to 650 nm. In addition, $Cu_2O$ has other several advantages such as non-toxicity, low cost and also can be prepared with simple and cheap methods on large scale. In this work, we deposited the $Cu_2O$ thin films by electrodeposition on gold coated $SiO_2/Si$ wafers. We changed the process conditions such as pH of the solution, applied potential on working electrode, and solution temperature. Finally, we confirmed the structural properties of the thin films by XRD and SEM.