• 한국분말재료학회지
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• 제21권1호
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• pp.34-38
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• 2014

Cu-Ni alloys with unidirectionally aligned pores were prepared by freeze-drying process of CuO-NiO/camphene slurry. Camphene slurries with dispersion stability by the addition of oligomeric polyester were frozen at $-25^{\circ}C$, and pores in the frozen specimens were generated by sublimation of the camphene during drying in air. The green bodies were hydrogen-reduced at $300^{\circ}C$ and sintered at $850^{\circ}C$ for 1 h. X-ray diffraction analysis revealed that CuO-NiO composite powders were completely converted to Cu-Ni alloy without any reaction phases by hydrogen reduction. The sintered samples showed large and aligned parallel pores to the camphene growth direction, and small pores in the internal wall of large pores. The pore size and porosity decreased with increase in CuO-NiO content from 5 to 10 vol%. The change of pore characteristics was explained by the degree of powder rearrangement in slurry and the accumulation behavior of powders in the interdendritic spaces of solidified camphene.

• 한국재료학회지
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• 제27권4호
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• pp.221-228
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• 2017

Various morphologies of copper oxide (CuO) have been considered to be of both fundamental and practical importance in the field of electronic materials. In this study, using Cu ($0.1{\mu}m$ and $7{\mu}m$) particles, flake-type CuO particles were grown via a wet oxidation method for 5min and 60min at $75^{\circ}C$. Using the prepared CuO, AlN, and silicone base as reagents, thermal interface material (TIM) compounds were synthesized using a high speed paste mixer. The properties of the thermal compounds prepared using the CuO particles were observed by thermal conductivity and breakdown voltage measurement. Most importantly, the volume of thermal compounds created using CuO particles grown from $0.1{\mu}m$ Cu particles increased by 192.5 % and 125 % depending on the growth time. The composition of CuO was confirmed by X-ray diffraction (XRD) analysis; cross sections of the grown CuO particles were observed using focused ion beam (FIB), field emission scanning electron microscopy (FE-SEM), and energy dispersive analysis by X-ray (EDAX). In addition, the thermal compound dispersion of the Cu and Al elements were observed by X-ray elemental mapping.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• 제4권4호
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• pp.201-208
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• 2000

The reduction of NO by hydrocarbons was investigated over Cu/Al$_2$O$_3$catalysts using a stainless steel flow reactor under highly oxidising diesel exhaust conditions(up to 15%). Three different Cu loadings(1,5 and 10wt.%) on an $Al_2$O$_3$support were prepared and characterized using spectroscopic techniques. The catalytic activity tests show that different Cu loadings as well as temperature, oxygen, and hydrocarbon concentration levels significantly influence the NO reduction. Increasing Cu loadings up to 5 and 10wt.% decreases the catalytic activities for NO reduction due to the formation of a bulk crystalline CuO phase, as observed from XRD and SEM images. In particular, the visualization of the copper dispersion on the surface using the SEM-BEI technique provides information on the extent of copper saturation, particle size, and the effects on NO reduction. However, the lower Cu loading(1 wt.%) increases the catalytic activity with a temperature window of 720-810K, thereby favoring the formation of well dispersed isolated Cu species, e.g. Cu(sup)2+ ions, which is related to selective NO reduction. The effects of other reaction parameters, such as oxygen, the hydrocarbon level and type, and byproduct emissions are further discussed.

• 한국분말재료학회지
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• 제16권4호
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• pp.280-284
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• 2009

The pressureless sintering behavior of $Al_2O_3$/Cu powder mixtures, prepared from $Al_2O_3$/CuO and $Al_2O_3$/Cu-nitrate, has been investigated. Microstructural observation revealed that $Al_2O_3$ powders with nano-sized Cu particles could be synthesized by hydrogen reduction method. The specimens, pressureless-sintered at $1400^{\circ}C$ for 4 min using infrared heating furnace with the heating rate of $200^{\circ}C$/min, showed the relative density of above 90%. Maximum hardness of 16.1 GPa was obtained in $Al_2O_3$/MgO/Cu nanocomposites. The nanocomposites exhibited the enhanced fracture toughness of 4.3-5.7 $MPa{\cdot}m^{1/2}$, compared with monolithic $Al_2O_3$. The mechanical properties were discussed in terms of microstructural characteristics.

• 한국세라믹학회지
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• 제49권5호
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• pp.417-422
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• 2012

Copper nano particles have been considered as the materials for conductive ink due to its good thermal, electrical conductivity and low cost. However, copper nanoparticles oxidize easily, decreasing dispersion stability and electrical conductivity. Therefore, it is important to develop a method to minimize oxidation of copper nano particles to improve its dispersion stability property in copper nano ink. In this study, copper nano particles were coated with 1-Octanethiol VSAM(Vaporized Self Assembled Multilayers) to prevent oxidation and coated copper powders were dispersed in conductive ink successfully by studying its relationship of different chain length of solvents to 1-Octanethiol coating layer to fabricate nano ink. Various alcohol solvents, such as 1-Hexanol, 1-Octanol, and 1-Decanol were used. The coating layer was observed using FESEM and TEM. Furthermore, dispersion of copper nano particles in nano inks, was characterized using Turbiscan analyzer, viscometer, and contact angle measurement tool.

• 자원환경지질
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• 제38권3호
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• pp.221-236
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• 2005

도시화$\cdot$산업화의 인위적 오염원에 의한 중금속 원소들의 분산양상과 오염특성을 파악하기 위하여 서울지역내의 은행나무 잎과 가로수 토양 시료를 채취하여 토양 pH와 Fe, Mn, Pb, Zn, Cu, Cd, Ni, Cr, Co등의 중금속 함량을 측정하였다. 서울지역의 대부분의 토양 pH는 6-9의 범위로 약산성 및 약알칼리성을 보였다. 토양에서 Cd-Co, Cr-Ni, Cu-Zn, Pb-Zn는 높은 상관성을 보이고 있어 Cd은 Co와 배출원이 유사하고, Cr은 Ni과 Zn는 Cu, Pb의 배출원이 유사함을 예측할 수 있었다. 가로수 토양과 은행나무 잎 시료에 대한 원소들의 분포특성은 세척하지 않은 은행나무 잎의 Cd과 Pb, Cu와 Zn의 오염양상이 유사하다. 세척하지 않은 은행나무 잎에서 Cr과 Ni이 유사한 분포패턴을 보였다. 토양에 대해 오염지수에 의하면 공단지역과 교통량 밀집지역에서의 오염도가 높고, 특히 Cd, Cu, Zn에 의한 오염이 심하다. 토양시료에 대한 판별분석결과, 주거지역과 전원지역에서보다 공단지역과 교통량 밀집지역에 부화되는 원소는 Ni> Cr>Pb 순이다. 공단지역과 교통량 밀집지역을 구분하는데 가장 큰 설명력을 가지는 원소는 Cd이며, 교통량 밀집지역에서는 다른 원소에 비해 Co, Pb, Zn가 부화되어 있다.

• Bulletin of the Korean Chemical Society
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• 제19권4호
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• pp.466-470
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• 1998

Catalytic hydrogenation of carbon dioxide for the simultaneous synthesis of methanol and dimethyl ether (together called oxygenates) over a combination of methanol synthesis and methanol dehydration catalysts has been studied. Various methanol synthesis and methanol dehydration catalysts were examined for this reaction. The addition of promotors like $Ga_2O_3\; and\; Cr_2O_3$ to Cu/ZnO catalyst gave much more enhanced yield on the formation of oxygenates. From the results, the promotional effect of $Cr_2O_3$ has been explained in terms of increase in the intrinsic activity of Cu while that of $Ga_2O_3$ being increase in the dispersion of Cu. Among the methanol dehydration catalysts examined, the solid acids bearing high population of intermediate-strength acid sites were found to be very effective for the production of oxygenates. HY zeolite which contains strong acid sites produce small amount of hydrocarbons as by-products. However, CuNaY zeolite in which the presence of strong acid sites are minimum gives very high oxygenates yield without the formation of hydrocarbons.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2005년도 춘계학술발표대회 개요집
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• pp.152-154
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• 2005

Austenitic stainless steel has good weldability but is sensitive to hot cracking such as solidification crack and liquation crack. In this study, the specimens of dissimilar metals made between austenitic stainless steel and Al-brass were welded by GTAW process using four different filler metals. Cracks were detected in the heat-affected zone of the stainless steel when welded with CuAl, CuSn and NiCu filler metals, but no cracks were detected a Ni filler metal was used. The cracks propagated along the grain boundary in the heat affected zone near the fusion line to base metal of 316L stainless steel. The cracks were located inside the weld bead with very fine hairline crack. All cracks initiated at the fusion line and moved forward in the base metal. From energy dispersion spectroscopy (EDS), Cu peak was detected only in the crack-opening area.

• 한국인쇄학회지
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• 제8권1호
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• pp.1-20
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• 1990

$\alpha$,$\beta$,$\varepsilon$ type copper phthalocy $\alpha$,$\beta$,$\varepsilon$ type copper phthalocyanine(CuPc) pigment was purified by a simple train sublimation technique. The layered photoconductor was made with $\varepsilon$ type CuPc as a carrier generation layer(CGL) and polyvinly carvazol(PVCz) as a carrier transport layer(CLT). A CGL of CuPc was electrochemical deposited on an Al substrate used as cathode in pigment dispersion solutions. a CTL of PVCz pwas spin coated on $\varepsilon$ type CuPc thin film by a spin coater. The effect of sonication time, electrophotographic property of the layered photoconductor were studied with surface coverage, surface potential and sensitivity.

• 한국분말재료학회지
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• 제7권1호
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• pp.12-18
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• 2000

Effects of the microstrucrure of rapidy solidified Al-Pb-Cu-Mg alloys on the wear investigated. In order to overcome the miscility gap between Al and pb under equilibrium conditions, both in the solid and the liquid states, the alloy were rapidy solidifies to produce them in a segregation-free condition. Although the Pb particles showed relatively fine dispersion in the Al matrix in all the alloys by this process. the Al-16Pb alloy was found to have the most favorable microstructure with discretre with discrete Pb particles of abount 0.5 ${\mu}$m in size. With the addition of Cu and Cu-Mg to Al-16Pb, cellular structures were newly formed; not seen in the binary Al-Pb alloy. Wear properties of the Al-Pb binary alloys measured as a function of the sliding speen, sliding distance, and applied load showed that the Al-16Pb alloy has the best wear resistance, as expected from the fine microstructural features in this alloy. The were resistance of the alloy containing Cu-and Cu-Mg was higher than that of the Al-16Pvb alloy, due to matrix strengthening by precipitation hardeing. The wear mechanism was identified by examining the traces and wear debris.