• Journal of the Korean institute of surface engineering
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• v.51 no.1
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• pp.47-53
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• 2018

Sn-based lithium-ion batteries have low cost and high theoretical specific capacity. However, one of major problem is the capacity fading caused by volume expansion during lithiation/delithiation. In this study, 3-dimensional foam structure of Cu-Sn alloy is prepared by co-electrodeposition including large free space to accommodate the volume expansion of Sn. The Cu-Sn foam structure exhibits highly porous and numerous small grains. The result of EDX mapping and XPS spectrum analysis confirm that Cu-Sn foam consists of $SnO_2$ with a small quantity of CuO. The Cu-Sn foam structure electrode shows high reversible redox peaks in cyclic voltammograms. The galvanostatic cell cycling performances show that Cu-Sn foam electrode has high specific capacity of 687 mAh/g at a current rate of 50 mA/g. Through SEM observation after the charge/discharge processes, the morphology of Cu-Sn foam structure is mostly maintained despite large volume expansion during the repeated lithiation/delithiation reactions.

• Korean Journal of Metals and Materials
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• v.48 no.12
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• pp.1056-1063
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• 2010

We present a new joining method for Pd-Cu membrane foils used as permeation tubes to collect $CO_2$. Since foils have poor mechanical strength, joining should be done at low temperatures to reduce residual stresses and without joining pressure. This contradicts the well known conditions for good contact between base materials that determines joint qualities. We selected Sn-Ag-Cu alloys that are highly reactive with Pd and Cu as a filler metal. As the filler melts at joining temperatures as low as $220{\sim}280^{\circ}C$, Pd and Cu are dissolved into the melt and react with the filler elements, which raises the melting temperature of the filler based on eutectic structures among the elements. Then, isothermal solidification progresses for the rest of the joining time. Intermetallic compounds (IMC) in the joints, one of the main factors for brittle joints, are inevitably formed. However, by optimizing both joining time and temperature, we balanced the wettability with IMC. Sealing test results confirmed that the joints are mechanically reliable during operation.

• Journal of Environmental Science International
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• v.27 no.2
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• pp.109-122
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• 2018

This study was conducted to investigate the removal characteristics of heavy metals and sulfate ion from acid mine drainage by porous zeolite-slag ceramics (ZS ceramics) that was prepared by adding wood flour as pore-foaming agent while calcining the mixtures of natural zeolite and converter slag. The batch test showed that the removal efficiency of heavy metals by pellet-type porous ZS ceramics increased as the particle size of wood flour was decreased and as the weight mixing ratio of wood flour to ZS ceramics was increased. The optimal particle size and weight mixing ratio of wood flour were measured to be $75{\mu}m$ and 7~10%, respectively. The removal test with the porous ZS ceramics prepared in these optimal condition showed very high removal efficiencies: more than 98.4% for all heavy metals and 73.9% for sulfate ion. Relative to nonporous ZS ceramics, the increment of removal efficiency of heavy metals by porous ZS ceramics with $75{\mu}m$ and 10% wood flour was 5.8%, 60.5%, 36.9%, 87.7%, 10.3%, and 57.4% for Al, Cd, Cu, Mn, Pb, and Zn, respectively. The mechanism analysis of removal by the porous ZS ceramics suggested that the heavy metals and sulfate ion from acid mine drainage are eliminated by multiple reactions such as adsorption and/or ion exchange as well as precipitation and/or co-precipitation.

• Analytical Science and Technology
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• v.28 no.3
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• pp.182-186
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• 2015

In this study, the porous CuO/MnO₂ catalyst was prepared through the co-precipitation process from an aqueous solution of potassium permanganate (KMnO₄), manganese(II) acetate (Mn(CH₃COO)₂·4H₂O) and copper(II) acetate (Cu(CH₃COO)₂·H₂O). The phase change in MnO₂ was analyzed according to the reaction molar ratio of KMnO₄ to Mn(CH₃COO)₂. The reaction mole ratio of KMnO₄ to Mn(CH₃COO)₂·4H₂O was varied at 0.3:1, 0.6:1, and 1:1. The aqueous solution of Cu(CH₃COO)₂ was injected into a mixed solution of KMnO₄ and Mn(CH₃COO)₂ to 10~75 wt% relative to MnO₂. The Cu ion co-precipitates as CuO with MnO₂ in a highly dispersed state on MnO₂. The physicochemical property of the prepared CuO/MnO₂ was analyzed by using the TGA, DSC, XRD, SEM, and BET. The different phase types of MnO₂ were prepared according to the reaction mole ratio of KMnO₄ to Mn(CH₃COO)₂·4H₂O. The results confirmed that the porous CuO/MnO₂ catalyst with γ-phase MnO₂ was produced in the reaction mole ratio of KMnO₄ to Mn(CH₃COO)₂ as 0.6:1 at room temperature.

• Applied Chemistry for Engineering
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• v.5 no.6
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• pp.1009-1015
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• 1994

Monodisperse porous poly(styrene-co-divinylbenzene)(St-DVB) gel and poly(acrylonitrile-co-ethylene dimethacrylate)(AN-EDMA) gel have been prepared by seed polymerization using polystyrene seeds, which were prepared by dispersion polymerization. The St-DVB and AN-EDMA gels had a narrow size distribution and pores suitable for packing materials of HPLC. The columns packed with these gels were proved to have high efficiency for GPC or HPLC coluuns. Adsorption properties of $Cu^{2+}$, $Cd^{2+}$ and ${UO_2}^{2+}$ ions on AAN-EDMA gel prepared from amidoximation of AN-EDMA gel were also determined.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.6 no.1
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• pp.13-26
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• 2001

Six ferromanganese crusts from the Lomilik and Litatfooki seamounts in the Marshall Islands were analyzed for texture, geochemistry and stratigraphy to delineate the paleoceanographic conditions. The crusts can be divided into three layers; 1) outermost massive layer (Layer 1), 2) middle porous Fe-oxides rich layer infllled with biointemal clasts (Layer 2), and 3) innermost massive layer cemented and/or replaced by carbonate fluoapatite (CFA) (Layer 3). The Layer 1 contains higher Mn, Co, Ni, and Mg than other two layers, and the Layer 2 was relatively more enriched in Fe, Al, Ti, Ba, Cu, and Zn. However, the Layer 3 shows higher Ca and P and lower Mn, Fe, Co, and Ni contents than overlying two layers. Based on the Co-chronometry, the crusts are postulated to have begun to grow from 56-31 Ma (early Eocene to Oligocene). The boundaries between layers 1 and 2, and layers 2 and 3 are dated to be 7-3 Ma and 26-14 Ma, respectively. High contents of Ca and P in Layer 3 clearly indicate that the layer had been phosphatized prior to the formation of Layer 2. Considering the well-preserved mjcrostructures in Layer 3, it is unlike that the crusts themselves were recrystallized in suboxic condition. Also, the lower Co concentrations in Layer 3 may imply that the Co supply was not constant during the formation of Layer 3. Layer 2, characterized by the porous texture, grew over Layer 3 during 26-9 Ma. Internal biogenic sediments including foraminifera within the original cavities and the enrichment of organophillic elements such as Ba, Cu, and Zn, suggest that Layer 2 have below high production regions. Also, high content of allumino silicate components may indicate increased terrigeneous input during the formation of Layer 2. The Layer 2. The Layer 1 has been subjected to little diagenetic influence since the Pliocene.

• Analytical Science and Technology
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• v.15 no.3
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• pp.263-269
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• 2002

After porous filters were manufactured using cordierite powder whose mean particle size was 200 ${\mu}m$, they were loaded with catalysts such as Pt, Pd, Cu, Co, La, $V_2O_5$ by vacuum impregnation method. And we investigated the activity of catalysts used for catalytic oxidation of VOC by passing toluene through catalyst-loaded filters. The porous filters had the apparent porosity of 62%, the compressive strength of about 10 MPa and the pressure drop of 15 mmHg at the face velocity of 5 cm/sec. The loading of catalyst decreased the porosity of the filters and increased the pressure drop and the compressive strength of them. Among the catalysts, Pt had the highest activity for catalytic oxidation and could remove more than 90% of toluene at 250 $^{\circ}C$. Below 250 $^{\circ}C$, the content of Pt catalyst had an influence on the conversion of toluene but didn't show any influence above 250 $^{\circ}C$.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2000.04a
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• pp.11-11
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• 2000

Large-size ceramic/metal bulk FGMs have been fabricated on a recently developed and the world's largest Spark Plasma Sintering(SPS) systems, As a part of the development program for practical production processes and machines for FGMs by SPS, the processes, mechanical properties, dimensional size and shape effects, and production machine systems were investigated. In the past, $ZrO_{2}$/TiAI, $ZrO_{2}$/Ni, $Al_{2}O_{3}$/Ti, WC/Co, WC/Co/Steel, A1/P, Polymide, Cu/Polymide, nano-composites, porous and other combinations of bulk FGMs have already been processed using SPS. However, most of the specimen sizes were small, in a range of 20 to 30mm in diameter. Recently disk-shape sintered compacts with diameters of 100 and 150 mm, and thickness of approximately 15 and 17 mm, $ZrO_{2}$(3Y)/ stainless steel FGMs were homogenous consolidated in a shorter sintering time, while maintaining high quality and repeatability by utilizing a temperature gradient sintering method. The SPS heating up and holding time totaled less than one hour. Therefore, the SPS process in expected to find increased use in the fabrication of large-size FGMs as a new industrial processing technology. This paper introduces SPS systems, the processing principles, features and the characteristies of ceramic/metal bulk FGM.

• Journal of Korean Society of Water and Wastewater
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• v.19 no.2
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• pp.228-237
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• 2005

The main purpose of this study was to investigate the red water reducing effects of phosphate based inhibitor when it was applied to water distribution system. The effects of pH, alkalinity, calcium concentration in the reduction of the red water also studied. The most finished water in Korea showed relatively high corrosiveness and was required to introduce some types of corrosion reducing methods such as addition of alkalinity. The precipitation of $CaCO_3$ by addition of $Ca(OH)_2$ formed porous film on the surface of the carbon steel pipes and was displaced easily from the surface of the pipes; on the other hand, addition of zinc phosphate (ZOP) formed reliable film on the surface and reduced iron release and color. Although the main function of ZOP was to suppress the release of Pb and Cu, it also reduced iron concentration released from water distribution pipes.

• Journal of Industrial and Engineering Chemistry
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• v.67
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• pp.448-460
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• 2018

Copper nanoparticle-doped and graphitic carbon nanofibers-covered porous carbon beads were used as an efficient catalyst for treating synthetic phenolic water by catalytic wet air oxidation (CWAO) in a packed bed reactor over 10-30 bar and $180-230^{\circ}C$, with air and water flowing co-currently. A mathematical model based on reaction kinetics assuming degradation in both heterogeneous and homogeneous phases was developed to predict reduction in chemical oxygen demand (COD) under a continuous operation with recycle. The catalyst and process also showed complete COD reduction (>99%) without leaching of Cu against a high COD (~120,000 mg/L) containing industrial wastewater.