• Journal of Korean Society of Environmental Engineers
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• v.38 no.8
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• pp.411-419
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• 2016

The objective of this study was to evaluate the application possibility of tube type electrolysis module system using recirculation process through removal organic matters and nitrogen in the pigment wastewater. The tube type electrolysis module consisted of a inner rod anode and an outer tube cathode. Material used for anode was titanium electroplated with $RuO_2$. Stainless steel was used for cathode. It was observed that the pollutant removal efficiency was increased according to the decrease of flowrate and increase of current density. When the retention time in tube type electrolysis module system was 180 min, chlorate concentration was 382.4~519.6 mg/L. The chlorate production was one of the major factors in electrochemical oxidation of tube type electrolysis module system using recirculation process used in this research. The pollutant removal efficiencies from the bench scale tube type electrolysis module system using recirculation operated under the electric charge of $4,500C/dm^2$ showed the $COD_{Mn}$ 89.6%, $COD_{Cr}$ 67.8%, T-N 96.8%, and Color 74.2%, respectively and energy consumption was $5.18kWh/m^3$.

• Resources Recycling
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• v.27 no.4
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• pp.29-35
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• 2018

In this study, the electrochemical redox behavior of neodymium in non-aqueous electrolytes was investigated to confirm the possibility of neodymium metallurgy at room temperature. The non-aqueous electrolytes include ionic liquids such as $[C_4mim]PF_6$, $[C_4mim]Cl$, and $[P_{66614}]PF_6$, ethanol which are highly soluble in neodymium salts, and mixed electrolytes based on carbonate with highly electrochemical stability. The electrochemical redox properties of neodymium were better than those of other electrolytes in the case of the mixed electrolyte based on ethylene carbonate (EC)/di-ethylene carbonate (DEC). Ethanol was added to improve the physical properties of the mixed electrolyte. Thorough the analysis about ionic conductivity of EC/DEC ratio, ethanol content and $NdCl_3$ concentration, the best electrolyte composition was 50 vol% content of ethanol and 0.5 M of $NdCl_3$. Using cyclic voltametry and linear sweep voltametry, a current peak estimated at -3.8 V (vs. Pt-QRE) was observed as a limiting current of neodymium reduction. Potentiostatic electrolysis for 18 hours at room temperature at -6 V (vs. Pt-QRE) confirmed that metallic neodymium was electrodeposited.

• Applied Chemistry for Engineering
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• v.10 no.3
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• pp.336-342
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• 1999

Various surface treatment techniques can be applied onto the surface of carbon fibers to increase interlaminar shear strength (ILSS). In a commerciaI treatment, first, surface of carbon fiber was oxidized, after that, a sizing agent was coated to improve handleability and adhesion to the matrix. Carbon fiber reinforced composites (CFRC) which is made of these fibers show excellent ILSS but show low vaIues of impact strength In this study, reactive and ductile interphase was introduced between fiber and matrix to increase both the ILSS and impact strength. By using electric conductivity of carbon fibers, flexible polymers which have ionizable group, i.e., MVEMA and EMA, were coated onto the surface (oxidized) of carbon fiber by the technique of electrodeposition. ILSS and impact strength of composites were evaluated according to the surface treatments, i.e., commercial sizing treatment, interphase introduction, and without sizing treatment. Izod impact strength and ILSS of CFRC were simultaneously improved in thc thickness range of $0.08{\sim}0.12{\mu}m$ of MVEMA interphase. Water resistance of the composites was decreased by introducing MVEMA interphase.

• Journal of the Korean Electrochemical Society
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• v.2 no.4
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• pp.213-217
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• 1999

The electrochemical characteristics of two distinct adsorption sites of H at the polycrystalline Pt/0.2 M LiOH aqueous electrolyte interface have been studied using the phase-shift method. At the forward and backward scans, the under-potentially deposited H (WD H) peak occurs on the cyclic voltammogram. The transition region on the phase-shift profile or the Langmuir adsorption isotherm occurs at ca. -0.66 to -0.96 V vs. SCE. At the transition region (ca. -0.66 to -0.96 V vs. SCE), the equilibrium constant (K) for H adsorption transits from 18.5 to $4.0\times10^{-5}$ and vice versa. Similarly, the standard free energy $({\Delta}G_{ads})$ of H adsorption transits from -7.2 to 25.1kJ/mol and vice versa. The under and over-potentially deposited H (UPD H and OPD H) on the poly-Pt surface act as two distinguishable electroadsorbed H species. An exothermic reaction occurs at the UPD H range. Both the UPD H peak and the transition region are attributed to the two distinct adsorption sites of the UPD H and OPD H on the poly-Pt surface.

• Journal of the Microelectronics and Packaging Society
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• v.18 no.2
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• pp.43-48
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• 2011

The maximum current density of copper electrorefining is 350 A/$m^2$ and the higher current density is required to promote the copper productivity. The 1000 A/$m^2$ high current density is possible when rotating disc electrode is employed to reduce diffusion thickness. The copper electroplating with 1000 A/$m^2$ is possible at 400 rpm. Thiourea and glue were used to improve the electrodeposition behaviors during copper electrorefining process. Potentiodynamic polarization tests were conducted to investigate the effects of additives on copper electrodeposition. Galvanostatic tests were also conducted at 1000 A/$m^2$. Copper were electroplated on cylindrical rotating electrodes to give the uniform flow on the electrode surface. The lowest surface roughness was obtained when 16 ppm thiourea was added to the electrolytes. The surface roughness was increased with glue concentration. The surface hardness was not influenced by addition of glue. The copper nuclei were getting smaller with thiourea concentration, however there is no glue effects on copper nucleation.

• Resources Recycling
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• v.31 no.3
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• pp.61-72
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• 2022

We investigated the electrochemical behavior of Sn (93.0 %)-Ag (4.06 %)-Cu (0.89 %) during electrolysis of Pb-free solder waste to recover tin and silver. A thin strip of the solder waste produced by high-temperature melting and casting was used as a working electrode to perform electrochemical analysis. During anodic polarization, the current peak of an active region decreased with an increase in the concentration of sulfuric acid used as an electrolyte. This resulted in the electro-dissolution of the working electrode in the electrolyte (1.0 molL^-1 sulfuric acid) for a constant current study. The study revealed that the thickening of an anode slime layer at the working surface continuously increased the electrode potential of the working electrode. At 10 mAcm^-2, the dissolution reaction continued for 25 h. By contrast, at 50 mAcm^-2, a sharp increase in the electrode potential stopped the dissolution in 2.5 h. During dissolution, silver enrichment in the anode slime reached 94.3% in the 1 molL^-1 sulfuric acid electrolyte containing a 0.3 molL^-1 chlorine ion, which was 12.7% higher than that without chlorine addition. Moreover, the chlorine enhanced the stability of the dissolved tin ions in the electrolyte as well as the current efficiency of tin electro-deposition at the counter electrode.

• Journal of the Korean Electrochemical Society
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• v.2 no.4
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• pp.237-241
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• 1999

The characteristics of copper thin films and via hole filling capability were investigated by pulsed electrodeposition method. Especially, the effects of additives on the properties of copper thin films were studied. Copper films, which were deposited by pulsed electrodeposition using commercial additives, had low tensile stress value under 83.4 MPa and high preferred Cu (111) texture. Via holes with $0.25{\mu}m$ in diameter and 6 : 1 aspect ratio were successfully filled without any defects by superfilling. It was observed that copper microstructure deformed by twining. After heat treatment at $500^{\circ}C$ for 1 k in vacuum furnace, grain size was 1 or 2 times as large as film thickness and the bamboo structure was formed. Heat treated copper films showed good resistivities of $1.8\~2.0{\mu}{\Omega}{\cdot}cm$.

• Journal of the Microelectronics and Packaging Society
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• v.19 no.2
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• pp.55-59
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• 2012

Defects such as voids or seams are frequently found in TSV via filling process. To achieve defect-free copper via filling, organic additives such as suppressor, accelerator and leveler were necessary in a copper plating bath. However, by-products stemming from the breakdown of these organic additives reduce the lifetime of the devices and plating solutions. In this research, the effects of levelers on copper electrodeposition were investigated without suppressor and accelerator to lower the concentration of additives. Threelevelers(janus green B, methylene violet, diazine black) were investigated to study the effects of levelers on copper deposition. Electrochemical behaviors of these levelers were different in terms of deposition rate. Filling performances were analyzed by cross sectional images and its characteristics were different with variations of levelers.

• Korean Journal of Materials Research
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• v.23 no.11
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• pp.638-642
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• 2013

Chalcopyrite $CuInSe_2$(CIS) is considered to be an effective light-absorbing material for thin film photovoltaic solar cells. CIS thin films have been electrodeposited onto Mo coated and ITO glass substrates in potentiostatic mode at room temperature. The deposition mechanism of CIS thin films has been studied using the cyclic voltammetry (CV) technique. A cyclic voltammetric study was performed in unitary Cu, In, and Se systems, binary Cu-Se and In-Se systems, and a ternary Cu-In-Se system. The reduction peaks of the ITO substrate were examined in separate $Cu^{2+}$, $In^{3+}$, and $Se^{4+}$ solutions. Electrodeposition experiments were conducted with varying deposition potentials and electrolyte bath conditions. The morphological and compositional properties of the CIS thin films were examined by field emission scanning electron microscopy (FE-SEM) and energy dispersive spectroscopy (EDS). The surface morphology of as-deposited CIS films exhibits spherical and large-sized clusters. The deposition potential has a significant effect on the film morphology and/or grain size, such that the structure tended to grow according to the increase of the deposition potential. A CIS layer deposited at -0.6 V nearly approached the stoichiometric ratio of $CuIn_{0.8}Se_{1.8}$. The growth potential plays an important role in controlling the stoichiometry of CIS films.

• Journal of the Microelectronics and Packaging Society
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• v.12 no.2 s.35
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• pp.129-134
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• 2005

Electroplating copper is the important role in formation of 3D stacking interconnection in SiP (System in Package). The I-V characteristics curves are investigated at different electrolyte conditions. Inhibitor and accelerator are used simultaneously to investigate the effects of additives. Three different sizes of via are tested. All via were prepared with RIE (reactive ion etching) method. Via's diameter are 50, 75, $100{\mu}m$ and the height is $100{\mu}m$. Inside via, Ta was deposited for diffusion barrier and Cu was deposited fer seed layer using magnetron sputtering method. DC, pulse and pulse revere current are used in this study. With DC, via cannot be filled without defects. Pulse plating can improve the filling patterns however it cannot completely filled copper without defects. Via was filled completely without defects using pulse-reverse electroplating method.