• Journal of the Korean Chemical Society
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• v.53 no.3
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• pp.233-243
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• 2009

We have investigated the infrared spectra for CO adsorbed on silica supported nickel(Ni-Si$O_2$), silica supported copper(Cu-Si$O_2$), silica supported nickel-copper alloys(Ni/Cu-Si$O_2$) of several compositions with varying CO pressures(0.2 $torr{\sim}$50 torr) at room temperature and on pumping to vacumn at room temperature within the frequency range of 1500 $cm^{-1}{\sim}2500\;cm^{-1}$. Four bands(2059.6 $cm^{-1},\;{\sim}$2036.5 $cm^{-1},\;{\sim}$ 1868.7 $cm^{-1},\;{\sim}$ 1697.1 $cm^{-1}$) were observed for Ni-Si$O_2$, two bands($\sim$2115.5 $cm^{-1},\;{\sim}$1743.0 $cm^{-1}$) were observed for Cu-Si$O_2$ and five bands(${\sim}2123.2\;cm^{-1}$, 2059.6 $cm^{-1},\;{\sim}$2036.4 $cm^{-1},\;{\sim}$1899.5 $cm^{-1},\;{\sim}$1697.1 $cm^{-1}$) were observed for Ni/Cu-Si$O_2$. These absorption bands correspond with those of the previous reports approximately. The bands below 1800 $cm^{-1}$ were only observed with Ni metal or Ni/Cu alloy crystal plane containing step at room temperature and the ${\sim}1697.1\;cm^{-1}$ bands observed with Ni-Si$O_2$ and Ni/Cu-Si$O_2$ may be ascribed to CO molecule adsorbed on the adsorption sites near step. The bands below 2000 $cm^{-1}$ were rarely observed with Cu metal crystal plane at room temperature and the 1743.0 $cm^{-1}$ bands may be ascribed to CO molecule adsorbed on the adsorption sites near step. The band shifts of adsorbed CO with varing Cu contents from 0 to 0.5 mole fraction at the same CO pressure or at the same pumping time to vacumn were below 21 $cm^{-1}$. and comparatively small than those with other ⅠB metal addition. It may means ligand effect of Cu d electron is small.

• Journal of Korea Foundry Society
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• v.17 no.4
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• pp.347-355
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• 1997

It is well known that the coarse primary Si in hypereutectic Al-Si alloys deteriorate castability, machinability, and mechanical properties. So, many treatment has been tried to refine the primary Si increasing cooling rate and adding refinement agent. Therefore. the purpose of our work was the observation of the effect on the refinement of primary Si and the analysis of the trend to apply to the casting process by changing the amount of P addition and the cooling rate while fixing the temperature at $750^{\circ}C$ of P addition and the type of AlCuP. In the condition of amount of P addition was fixed, primary Si was finer as cooling rate increased but in case of cooling rate was fixed, the effect of refinement was resisted as incersed the amount of P addition. At a relatively slow cooling rate of $22^{\circ}C/sec$, refinement was governed by the amount of P addition rather than cooling rate. At elevated cooling rate of $51^{\circ}C/sec$ and $99^{\circ}C/sec$, the undercooling due to faster cooling rate promoted nucleation of primary Si rather than P addition more significantly.

• Proceedings of the Korean Magnestics Society Conference
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• 2004.12a
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• pp.107-108
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• 2004

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.230-233
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• 2004

The stochiometric mix of evaporating materials for the $CuInS_2$ single crystal thin films was prepared from horizontal furnance. Using extrapolation method of X-ray diffraction patterns for the $CuInS_2$ polycrystal, it was found tetragonal structure whose lattice constant $a_0$ and $c_0$ were $5.524\;{\AA}$ and $11.142\;{\AA}$, respectively. To obtain the single crystal thin films, $CuInS_2$ mixed crystal was deposited on throughly etched semi-insulator GaAs(100) substrate by the hot wall epitaxy (HWE) system. The source and substrate temperature were 640 t and 430 t, respectively and the thickness of the single crystal thin films was $2{\mu}m$. Hall effect on this sample was measured by the method of van dot Pauw and studied on carrier density and temperature dependence of mobility. The carrier density and mobility deduced from Hall data are $9.64{\times}10^{22}/m^3,\;2.95{\times}10^{-2}\;m^2/V{\cdot}s$ at 293 K, respectively The optical energy gaps were found to be 1.53 eV at room temperature. From the photocurrent spectrum by illumination of perpendicular light on the c - axis of the thin film, we have found that the values of spin orbit coupling splitting ${\Delta}So$ and the crystal field splitting ${\Delta}Cr$ were 0.0211 eV and 0.0045 eV at 10 K, respectively. From PL peaks measured at 10K, 807.7nm (1.5350ev) mean Ex peak of the free exciton emission, also 810.3nm (1.5301eV) expresses $I_2$ peak of donor-bound exciton emission and 815.6nm (1.5201eV) emerges $I_1$ peak of acceptor-bound exciton emission. In addition, the peak observed at 862.0nm (1.4383eV) was analyzed to be PL peak due to donor-acceptor pair(DAP).

• Corrosion Science and Technology
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• v.17 no.4
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• pp.154-165
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• 2018

During the process of sulfur dioxide removal, flue gas desulfurization equipment provides a serious internal corrosion environment in creating sulfuric acid dew point corrosion. Therefore, the utilities must use the excellent corrosion resistance of steel desulfurization facilities in the atmosphere. Until now, the trend in developing anti-sulfuric acid steels was essentially the addition of Cu, in order to improve the corrosion resistance. The experimental alloy used in this study is Fe-0.03C-1.0Mn-0.3Si-0.15Ni-0.31Cu alloys to which Ru, Zn and Ta were added. In order to investigate the effect of $H_2SO_4$ concentration and the alloying elements, chemical and electrochemical corrosion tests were performed. In a low concentration of $H_2SO_4$ solution, the major factor affecting the corrosion rate of low alloy steels was the exchange current density for $H^+/H_2$ reaction, while in a high concentration of $H_2SO_4$ solution, the major factors were the thin and dense passive film and resulting passivation behavior. The alloying elements reducing the exchange current density in low concentration of $H_2SO_4$, and the alloying elements decreasing the passive current density in high concentration of $H_2SO_4$, together play an important role in determining the corrosion rate of Cu-bearing low alloy steels in a wide range of $H_2SO_4$ solution.

• Progress in Superconductivity and Cryogenics
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• v.5 no.3
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• pp.1-5
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• 2003

The effect of CeO$_2$ coating on the surface nucleation of the top-seeded melt-growth processed YBCO superconductors was studied. It was effective that the coating of Y123 compact surfaces by CeO$_2$ powder suppressed the undesirable subsidiary YBa$_2$Cu$_3$O$_{7-y}$ (Y123) nucleation during melt processing. BaCeO$_3$ was formed in the CeO$_2$-coated layers, which might cause a CuO-excessive liquid at the partial melt stage of $Y_2$BaCuO$_{5}$(Y211) plus liquid, and thus the Y123 nucleation at the YBCO compact surfaces could be suppressed during the melt growth of Y123 grain. In addition, the CeO$_2$ refined the Y211 particles near the compact / coating interface. While the levitation forces of the top surfaces with and without CeO$_2$ coating were similar to each other, the levitation force of the interior of the CeO$_2$ coated sample was higher than that of the interior of the sample without CeO$_2$ coating, which was attributed to the suppression of subsidiary Y123 nucleation at the compact walls.s.s.

• Journal of Surface Science and Engineering
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• v.29 no.6
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• pp.683-690
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• 1996

In this study, the diffusion barrier properties of $1000 \AA$ thick molybdenum compounds (Mo, Mo-N, $MoSi_2$, Mo-Si-N) were investigated using sheet resistance measurements, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Scanning electron microscopy (SEM), and Rutherford backscattering spectrometry (RBS). Each barrier material was deposited by the dc magnetron sputtering, and annealed at 300-$800^{\circ}C$ for 30min in vacuum. Mo and $MoSi_2$ barrier were failed at low temperature due to Cu diffusion through grain bound-aries and defects of Mo thin film and the reaction of Cu with Si within $MoSi_2$ respectively. A failure temperature could be raised to $650^{\circ}C$-30min in the Mo barrier system and to $700^{\circ}C$-30min in the Mo-silicide system by replacing Mo and $MoSi_2$ with Mo-N and Mo-Si-N, respectively. The crystallization temperature in the Mo-silicide film was raised by the addition of $N_2$. It is considered that not only the N, stuffing effect but also the variation of crystallization temperature affects the reaction of Cu with Si within Mo-silicide. It was found that Mo-Si-N is more effective barrier than Mo, $MoSi_2$, or Mo-N to copper penetration preventing Cu reaction with the substrate for 30min at a temperature higher than $650^{\circ}C$.

• Journal of The Korean Society of Grassland and Forage Science
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• v.24 no.3
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• pp.183-192
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• 2004

This pot experiment was conducted to investigate the effects of systematic variation application of Fe, Mn, Cu, and Zn on forage performance of orchardgrass and white clover. The treatments of systematic variation were 0/100, 25/75, 50/50. 75/25, and $100/0\%$ in the Fe/Cu(trial-1). Mn/Zn(trial-2), and Fe+Cu/Mn+Zn(trial-3), respectively The treatments of Fe/Mn/Cu/Zn(trial-4) were composed of $70\%$ for main element and $10\%$ for other 3 elements, respectively. 1. The contents of N-compounds in forages tended to be in inverse proportion to the yields. In the Mn/Zn trial, the 0/l00 to white clover resulted in the relatively high contents of soluble N-compounds and low ratio of pure protein/soluble N-compounds in company with a severe yield decrease. 2. In the Fe+Cu/Mn+Zn trial, the 0/100 and 100/0 resulted in the somewhat high contents of N-compounds in white clover. It was likely to be caused by the concentration effect derived from yield decrease. In addition, the 100/0 resulted in the relatively high content of soluble N-compounds and low ratio of pure protein/soluble N-compounds. The protein synthesis in white clover was likely to be negatively influenced by the 100/0. 3. In the Fe/Mn/Cu/Zn trial, white clover showed the low contents of crude and pure protein at the 1st cut. It was likely to be caused by the unbalanced mutual ratios derived from the high application levels of each single element. 4. In white clover at the 5th cut, the 0/100 of Mn/Zn and 100/0 of Fe+Cu/Mn+Zn resulted in the relatively high content of K. It was likely to be caused by the concentration effect derived from yield decrease.

• Journal of the Korean Ceramic Society
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• v.29 no.8
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• pp.639-645
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• 1992

Effects of additives on electromagnetic properties of a Ni-Cu-Zn ferrite for a noise filter in high frequency regions were studied. Both resistivity and permeability were increased with the amount of Mn2O3 up to 1wt%, then decreased with further addition. Addition of Co2O3 decreased the permeability of the ferrite and shifted the resonance frequency to a higher frequency region, which was thought due to the stabilization of domain walls. Therefore it was possible to improve both the permeability and the loss and to control the cut-off frequency by the concurrent addition of Mn2O3 and Co2O3.

• Journal of the Korean Society of Industry Convergence
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• v.4 no.1
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• pp.61-69
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• 2001

Polycarbonate(PC) membranes for oxygen enrichment from air were prepared by the wet phase inversion method. In order to improve oxygen separation performances of the PC membrane, the effect of the added ethanol(nonsolvent) and $CuCl_2$(metal salt) concentration in the casting solution on morphology, oxygen permeability ami $O_2/N_2$ separation factor of the membrane was studied. In addition, tensile strength and elongation at break of the membrane were investigated. An asymmetric membrane with a dense top layer and a porous sublayer was obtained. The thickness of the dense top layer decreased with increasing amount of nonsolvent additive. Compared with pure PC membrane without additive(metal salt), the oxygen permeability and $O_2/N_2$ separation factor of the $PC/CuCl_2$ membrane are significantly improved. The oxygen permeability and $O_2/N_2$ separation factor is $5.25{\times}10^{-9}cm^3(STP){\cdot}cm/cm^2{\cdot}sec{\cdot}cmHg$ and 4.5, respectively. This improvement might be due to good interaction between metal salt and oxygen.