• Journal of Surface Science and Engineering
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• v.49 no.2
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• pp.111-118
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• 2016

A method to quantitatively analyze the defects formed by the hydrogen evolution during electroplating was suggested based on the theoretical approach of the small angle neutron scattering technique. In case of trivalent chrome layers, an isolated defect size due to the hydrogen evolution was about 40 nm. Direct and pulse plating conditions gave the average defect size of about 4.9 and $4.5{\mu}m$ with rod or calabash shape, respectively. Current density change of the pulse plating from $1.5A/dm^2$ to $2.0A/dm^2$ enlarged the average defect size from 3.3 to $7.8{\mu}m$. The defect morphology like rod or calabash was originated by inter-connecting the isolated defects. Small angle neutron scattering was useful to quantitatively evaluate defect morphology of the deposit.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2005.11a
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• pp.196-197
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• 2005

Cathodic protection is one of the successful ways to prevent corrosion of steel structures in marine environments. The unique feature of cathodic protection in seawater is the formation of calcareous deposits on cathodic metal surface. The formation principles of calcareous deposit seawater had been known for a long time. That is, cathodic reduction reactions associated with cathodic protection in seawater generate $OH^-$ at the metal surface in accordance with the formular ; 1/2 $O_2$ + $H_2O$ + $2e^-$ $2OH^-$ and $2H_2O$ + $2e^-$ ${\rightarrow}$ $H_2$ + $2OH^-$. These reactions increase the pH at the metal / seawater interface. The high pH causes precipitation of $Mg(OH)_2$ and $CaCO_3$ in accordance with the formular ; $Mg^{2+}$ + $2(OH)^-$ ${\rightarrow}$ $Mg(OH)_2$ and $Ca^{2+}$ + $HCO_3^-$ + $OH^-$ ${\rightarrow}$ $H_2O$ + $CaCO_3$. These are typically the main compounds in calcareous deposits. It obviously has several advantages compared to the conventional coatings, since the environment-friendly calcareous deposit coating is formed by the elements($Mg^{2+}$, $Ca^{2+}$) naturally present in seawater. In this study, environmental friendly calcareous deposit films were prepared on steel plates by electro plating technic in natural seawater. The influence of current density on composition ratio, structure and morphology of the coated films were investigated by scanning electron microscopy formation process of calcareous deposits films in natural seawater. And we confirmed the properties of all the films can be improved greatly by controlling the material structure and morphology with effective use of the electroplating method in natural seawater.

• Journal of Advanced Marine Engineering and Technology
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• v.28 no.6
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• pp.1000-1009
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• 2004

The environment friendly calcareous deposit films were formed on steel plates by electrodeposition technique in natural seawater and synthetic solutions such as dissolved $\textrm{Mg}^{2+}$ and $\textrm{Ca}^{2+}$ ions at various potential conditions. The influence of potential conditions on composition ratio, structure and morphology of the electrodeposited films were investigated by scanning electron microscopy(SEM), energy dispersive spectroscopy(EDS) and X-ray diffractor (XRD). Accordingly, this study was provided a better understanding of the composition between the growth of $\textrm{Mg(OH)}_2$ and that of $\textrm{CaCO}_3$ during the formation of calcareous deposit films on steel substrate under cathodically electrodeposition in synthetic and natural seawater. The results showed that the formation of good overall calcareous deposited film in seawater can be achieved by controlling the Ca/Mg ratio according to interfacial pH with the effective use of the electro deposition technique.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1922-1927
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• 2008

In the present study, deposition of discrete and small particles, which diameter is less than $1{\mu}m$, on a filter element was simulated by stochastic method. Trajectory of each particle was numerically solved by Langevin equation and Brownian random motion was treated by Brownian dynamics. Lattice Boltzmann method (LBM) was used to solve flow field around the filter collector and deposit layer. Interaction between flow field and deposit layer was obtained from a converged solution from an inner-loop calculation. Simulation method is properly validated and collection efficiency due to different filtration parameters are examined and discussed. Morphology of deposit layer and its evolution was visualized in terms of the particle size. The particle loaded effect on collection efficiency was also discussed.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.7 no.3
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• pp.456-464
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• 1997

The effect of the additives on the Zn-Ni alloy electrocrystallization from a chloride bath was investigated by means of electrochemical methodes, scanning electron microscopy and measurement of surface appearance, X-ray diffraction patterns. The additives tested were the surfactant of naphtalene-derivative, saccharin and aliphatic alcohol. The resistance of electrodeposit increased by adding the additives, whereas the effect of additives on resistance was different with current density. The nickel content of alloy deposit was increased by the addition of alcohol, while decreased by the surfactant. The surface roughness, appearance and morphology of deposit were also influenced by the type of additive. The fine, compact grains and good surface roughness could be obtained from the surfactant or alcohol -added bath, and the surfactant or saccharin improved the surface appearance.

• Journal of Surface Science and Engineering
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• v.36 no.2
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• pp.155-160
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• 2003

The effect of the temperature, current density and deposit time on hard chromium deposition in trivalent chromium bath was investigated. Cathode current efficiency increased with increasing current density. Increasing bath temperature from $20^{\circ}C$ to $50^{\circ}C$, chromium deposits were produced in higher current density and the maximum current efficiency was increased. At the plating conditions of $40^{\circ}C$, $30A/dm\m^2$, the deposition thickness increased in proportion to increasing electrolysis time The rate is$ 90\mu\textrm{m}$/hrs. for 2 hours. Microhardness of chromium deposits increased with increasing bath temperature and decreasing current density, and it was constant with electrolysis time. All of bath conditions, microstructure of chromium deposits has nodular structure with some cracking pattern and nodule size increased with increasing deposit thickness.

• Journal of Surface Science and Engineering
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• v.17 no.2
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• pp.41-58
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• 1984

Zinc was electrodeposited from cyanide solutions at temperature from 20$^{\circ}C\;to\;40^{\circ}C$ in the range of current density from 0.5 to 8A/$dm^2$. The preferred orientation changed from (10.3)+(11.0) to (11.0) texture with increasing cathode overpotential in the additive free solution, while the (11.0) preferred orientation developed at lower overpotentials (800-1270 mV) and the (11.0)+(10.0) preferred orientation was formed at higher overpotential (1300-1400mV) in the solution with brightner. Mossy type of morphology developed mostly in the additive free deposits and the microstructure of the cross section of the above deposits changed from columar structure to granular structure with increasing overpotential. The surface appearance of the deposits with additive having (11.0) texture was the smooth deposit of very small crystallite, while that of the deposits having (11.0)+(10.0) texture was fine crystalline deposit. The microstructure of the cross section of them was the fine field oriented type of structure.

• Clean Technology
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• v.11 no.3
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• pp.153-164
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• 2005

This study found a reliable evaluation for four kinds of pb-Free plating solutions and it's layers, through pure Sn, SnAg, SnBi and SnCu. These four kind of solutions are widely used to pb-Free plating. Hull-cell, Harring-blum, coverage, throwing power, current efficiency, stability, life-time, composition, hardness, roughness, abrasion, scratch, solderability, corrosion, contact angle, morphology, SIR(Surface insulation resistance) and Whisker test were experimented. Also, Using ICP, XRF, FE-SEM, EDS, temperature/humidity chamber, solderability tester, hardness tester, roughness tester, abrasion tester, salt spray tester, contact angle tester, SIR tester, and microscope. In this paper could be shown the systematic and various analysis for reliability about four kinds of pb-Free plating solutions, processes and it's deposit surface.

• Journal of Surface Science and Engineering
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• v.36 no.2
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• pp.168-175
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• 2003

The purpose of solder plating on chip external electrode is to provide a proper solderability to chips on PCB's. The quantitative or qualitative analysis of solderability has been performed by destructive methods, reflow or flow. Evidently, the solderability tends to depend on the grain structure which is varied with additives. Research on the feasibility of employing electrochemical techniques to characterize the solderability of electroplated tin - lead, with respect to the additives, was non destructively performed. The deposit morphology and the polarization behavior of electrolytes containing proprietary additives were evaluated to investigate the soldering degradation. The plated panels from synthetic electrolyte were analyzed according to % Sn, plating thickness, deposit appearance, grain structure, solderability and cyclic voltammetry.

• Resources Recycling
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• v.14 no.1
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• pp.55-63
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• 2005

This study investigated the electrochemical recovery of palladium in a HCl solution that is used for palladium leaching. The high acidity of HCl solution and the low concentration of Pd ions increased the cathodic overpotential and reduced the limiting current density. Lowering the current density produced dense deposits; however, they were under high tensile stress. Raising the temperature affected both the densification and the stress, which enabled the attainment of dense Pd deposits under low stress. Lowering the current density and raising the temperature up to 70$^{\circ}C$ was recommended for the recovery of palladium as sound bulk Pd deposits. Current efficiency was over 85% at the initial stage of recovery may decrease the current efficiency, since a low Pd ion concentration results in a low limiting current density.