• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.10a
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• pp.301-301
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• 2003

In current study, Nanocomposites are reinforced with carbon nanofiber, carbon nanotube and SiC, etc. Since the nano reinforcements have the excellent mechanical, thermal and electrical properties compared with that of existing composites, it has lately attracted considerable attention in the various areas. Cu have been widely used as signal transmission materials for electrical electronic components owing to its high electrical conductivity. However, it's size have been limited to small ones due to its poor mechanical properties. Until now, strengthening of the copper alloy was obtained either by the solid solution and precipitation hardening by adding alloy elements or the work hardening by deformation process. Adding the alloy elements lead to reduction of electrical conductivity. In this aspect, if carbon nanofiber is used as reinforcement which have outstanding mechanical strength and electric conductivity, it is possible to develope Cu matrix nanocomposite having almost no loss of electric conductivity. It is expected to be innovative in electric conducting material market. The unidirectional alignment of carbon nanofiber is the most challenging task developing the cooer matrix composites of high strength and electric conductivity. In this study, the unidirectional alignment of carbon nanofibers which is used reinforced material are controlled by drawing process and align mechanism as well as optimized drawing process parameter are verified via numerical analysis. The materials used in this study were pure copper and the nanofibers of 150nm in diameter and of 10∼20$\mu\textrm{m}$ in length. The materials have been tested and the tensile strength was 75MPa with the elongation of 44% for the copper. it is assumed that carbon nanofiber behave like porous elasto-plastic materials. Compaction test was conducted to obtain constitutive properties of carbon nanofiber Optimal parameter for drawing process was obtained by analytical and numerical analysis considering the various drawing angles, reduction areas, friction coefficient, etc. The lower drawing angles and lower reduction areas provides the less rupture of co tube is noticed during the drawing process and the better alignment of carbon nanofiber is obtained.

• Applied Chemistry for Engineering
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• v.25 no.5
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• pp.531-537
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• 2014

A catalytic plasma reactor was employed for the oxidation of isopropyl alcohol (IPA) classified as a volatile organic compound (VOC). Copper oxide (Cu : 0.5% (w/w)) supported on a multichannel porous ceramic consisting of ${\alpha}-Al_2O_3$ was used as a catalyst, which was directly exposed to the plasma created in it. The effects of discharge voltage and reaction temperature on the concentrations of IPA and its byproducts were examined to understand the behavior of the catalytic plasma reactor. Without thermal insulation, the reactor temperature increased up to $120^{\circ}C$ at an applied voltage of 17 kV (discharge power : 28 W), and the IPA at a flow rate of $1L\;min^{-1}$ ($O_2$ : 10% (v/v); IPA : 1000 ppm) was completely removed. At temperatures below $120^{\circ}C$, however, besides the desirable product $CO_2$, several unwanted byproducts such as acetone, formaldehyde and CO were also formed from IPA. On the other hand, when the reactor was thermally insulated, the plasma discharge increased the temperature up to $265^{\circ}C$ under the same condition and most of IPA was oxidized to $CO_2$. Without loading CuO on the ceramic support, the plasma discharge in the thermally insulated reactor produced nearly equal amounts of $CO_2$ and CO. On comparison, with the catalyst alone (temperature : $265^{\circ}C$), more than 70% of the removed IPA was simply converted into another type of VOC (acetone), indicating that the catalyst assisted by the plasma is more effective in the oxidation of IPA than that of the catalyst-alone process.

• Journal of the Korean Electrochemical Society
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• v.13 no.4
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• pp.270-276
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• 2010

Nickel-copper foam electrodes with pore gradient micro framework and nano-ramified wall have been prepared by using an electrochemical deposition process. Growth habit of nickel-copper co-deposits was quite different from that of pure nickel deposit. In particular, the ramified structure of the individual particles was getting clear with chloride ion content in the electrolyte. The ratio of nickel to copper in the deposits decreased with the distance away from the substrate and the more chloride ions in the electrolyte led to the more nickel content throughout the deposits. Compositional analysis for the cross section of a ramified branch, together with tactical selective copper etching, proved that the copper content increased with approaching central region of the cross section. Such a composition gradient actually disappeared after heat treatment. It is anticipated that the pore gradient nickel-copper nanostructured foams presented in this work might be a promising option for the high-performance electrode in functional electrochemical devices.

• Clean Technology
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• v.20 no.4
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• pp.375-382
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• 2014

This work investigated the plasma-catalytic decomposition of isopropyl alcohol (IPA) and the behavior of the byproduct compounds over monolith-supported metal oxide catalysts. Iron oxide ($Fe_2O_3$) or copper oxide (CuO) was loaded on a monolithic porous ${\alpha}-Al_2O_3$ support, which was placed inside the coaxial electrodes of plasma reactor. The IPA decomposition efficiency itself hardly depended on the presence and type of metal oxides because the rate of plasma-induced decomposition was so fast, but the behavior of byproduct formation was largely affected by them. The concentrations of the unwanted byproducts, including acetone, formaldehyde, acetaldehyde, methane, carbon monoxide, etc., were in order of $Fe_2O_3/{\alpha}-Al_2O_3$ < $CuO/{\alpha}-Al_2O_3$ < ${\alpha}-Al_2O_3$ from low to high. Under the condition (flow rate: $1L\;min^{-1}$; IPA concentration: 5,000 ppm; $O_2$ content: 10%; discharge power: 47 W), the selectivity towards $CO_2$ was about 40, 80 and 95% for ${\alpha}-Al_2O_3$, $CuO/{\alpha}-Al_2O_3$ and $Fe_2O_3/{\alpha}-Al_2O_3$, respectively, indicating that $Fe_2O_3/{\alpha}-Al_2O_3$ is the most effective for plasma-catalytic oxidation of IPA. Unlike plasma-alone processes in which tar-like products formed from volatile organic compounds are deposited, the present plasma-catalyst hybrid system did not exhibit such a phenomenon, thus retaining the original catalytic activity.