• Journal of Advanced Marine Engineering and Technology
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• v.33 no.3
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• pp.387-394
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• 2009

It has been observed that coated steel structures are rapidly deteriorated than designed lifetime due to acid rain caused by air pollution etc.. Therefore improvement of corrosion resistance of anti-corrosive paint is very important in terms of safety and economic point of view. In this study corrosion resistance for five kinds of anti-corrosive paints including acryl, fluorine and epoxy resin series were investigated with electrochemical methods such as corrosion potential, polarization curves, impedance and cyclic voltammogram measurements etc.. There were somewhat good relationships between values measured by electrochemical methods such as corrosion current density obtained by cathodic and anodic polarization curves, value of impedance estimated with AC impedance, and polarization resistance on the cyclic voltammogram, for example, corrosion current density was decreased with increasing of values of impedance and polarization resistance on the cyclic voltammogram. However their relationships between corrosion current density and corrosion potential were not well coincided each other. Consequently it is considered that although a corrosion potential of F101 of fuoric resin series shifted to negative direction than other anti-corrosive paints, its corrosion resistance, indicating on the cathodic and anodic polarization curves, AC impedance curves and cyclic voltammogram, was the most superior to other paints, whereas A100 containing arcylic resin showed a relatively poor corrosion resistance compared to other paints.

• Journal of Electrochemical Science and Technology
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• v.7 no.4
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• pp.293-297
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• 2016

Here we propose a new equation by which we can estimate the baseline for measuring the peak current of the reverse curve in a cyclic voltammogram. A similar equation already exists, but it is a linear algebraic equation that over-simplifies the voltammetric curve and may cause unpredictable errors when calculating the baseline. In our study, we find a quadratic algebraic equation that acceptably reflects the complexity included in a voltammetric curve. The equation is obtained from a laborious numerical analysis of cyclic voltammetry simulations using the finite element method, and not from the closed form of the mathematical equation. This equation is utilized to provide a virtual baseline current for the reverse peak current. We compare the results obtained using the old linear and new quadratic equations with the theoretical values in terms of errors to ascertain the degree to which accuracy is improved by the new equation. Finally, the equations are applied to practical cyclic voltammograms of ferricyanide in order to confirm the improved accuracy.

• Applied Chemistry for Engineering
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• v.2 no.4
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• pp.311-329
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• 1991

Electrochemical behavior of surface active Osmium bipyridine complex adsorbed in a monomolecular layer on tin oxide electrodes by the Langmuir-Blodgett method was studied. Theoretical equation of cyclic voltammetry of electrode reactions for redox species adsorbed as monolayer form was discussed by reversible and quasi-reversible waves. The film was transferred onto the $SnO_2$ electrode surface and then amounts of charge on the electrode were measured in the technique of cyclic voltammetry. The electron transfer mediation of these monolayer with $Fe^{2+}$, TEMPOL and others were studied. And the cyclic voltammetry were simulated by taking into account the interaction parameters. From these values, we found it possible to fit almost all measured cyclic voltammograms with these parameters. The recent works and directions using LB method were introduced with various applicable field.

• Journal of the Korean Applied Science and Technology
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• v.20 no.2
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• pp.94-100
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• 2003

We studied electrochemical characteristics of Langmuir-Blodgett(LB) films by using cyclic voltammetry with a three-electrode system. An Ag/AgCl as a reference electrode, a platinum wire as a counter electrode and LB film-coated indium tin oxide(ITO) as a working electrode were used to study electrochemical characteristics at a various concentration of $NaClO_4$ solution. LB films were reduced from initial potential to -1350 mV, continuously oxidized to l650mV and returned to the initial point. The scan rate was l00mV/s. The monolayer surface morphology of the LB film have been measured by Atomic Force Microscope(AFM). As a result, We comfirmed that the microscopic properties of LB film by AFM showed the good orientation of momolayer molecules and the thickness of monolayer was 3.5-4.lnm. The cyclic voltammograms(CV) of the ITO-coated glass showed the peak potentials for the reduction-oxidation reation. LB films of 4-octyl-4'-(5-carboxypentamethyleneoxy) azobenzene(8A5H) / L-${\alpha}$-phosphayidyl choline, dilauroyl(DLPC) seemed to be irreversible process caused by only the oxidation current from the cyclic voltammogram. The current of oxidatation increased at cyclic voltammogram by increasing 8A5H density in LB films. The diffusivity(D) of LB films increased with increasing of a 8A5H amount and was inversely proportional to the concentration of $NaClO_4$ solution.

• Journal of the Korean Electrochemical Society
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• v.1 no.1
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• pp.8-13
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• 1998

This work presents the way how to evaluate the degree of reversibility of the discharging process undergone by the nickel hydroxide film cathodically deposited on pure nickel as a positive electrode for electrochemical capacitor using the combined cyclic voltammetry and potential drop method, supplemented by galvanostatic discharge and open-circuit potential transient methods. The time interval necessary just to establish the current reversal of anodic to cathodic direction from the moment just after applying the potential inversion of anodic to cathodic direction, was obtained on cyclic voltammogram. The cathodic charge density passed upon dropping the applied potential, was calculated on potentiostatic current density-time curve. Both the time interval and the cathodic charge density in magnitude can be regarded as being measures of the degree of reversibility of the discharging process undergone by the positive active material for supercapacitor, i.e. , the longer the time interval is, the lower is the degree of reversibility and the greater the cathodic charge density is, the higher is the degree of reversibility. From the applied potential dependences of the time interval and cathodic charge density, discharge at $0.42 V_{SCE}$ was determined to be the most reversible.

• 한국전기화학회:학술대회논문집
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• 1999.04a
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• pp.76-76
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• 1999

• Journal of Advanced Marine Engineering and Technology
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• v.29 no.5
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• pp.495-501
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• 2005

Al is a active metal that owes its resistance to a thin, protective, barrier oxide surface layer, which is stable in air and neutral aqueous solution. Thus Al alloys are widely used in architectural trim. cold & hot-water storage vessels and piping. However Al and most of its alloy may corrode with some forms such as pitting corrosion, intergranular corrosion and galvanic corrosion in the case of exposure to various industrial and marine atmosphere. Therefore a correct evaluation of corrosion resistance for their Al and Al alloys may be more important in a economical point of view. In this study. a relative evaluation of corrosion resistance for three kinds of Al alloys such as ALDC2, ALDC3, and ALDC8 series was carried out with electrochemical method. There is a tendency that corrosion potential is shifted to positive or negative direction by alloying components regardless of corrosion resistance. Moreover the data of corrosion properties obtained from cathodic Polarization curve, cyclic voltammogram and AC. DC impedance respectively showed a good correspondence each other against the corrosion resistance but variation of corrosion potential. passivity current density of anodic polarization curve and corrosion current density by Tafel extrapolation and Stern-Geary method didn't correspond with not only each other but also considerably the data of corrosion properties discussed above. Therefore it is suggested that an optimum electrochemical evaluation for corrosion resistance of Al alloy is to calculate the diffusion limiting current density of cathodic polarization curve, impedance of AC or DC and polarization resistance of cyclic voltammogram.

• Journal of the Korean Electrochemical Society
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• v.2 no.2
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• pp.93-97
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• 1999

From the anodic peak currents of cyclic voltammograms for Ag(I)/Ag(II) couple obtained with the variation of nitric acid concentration, Ag(I) concentration and solution temperature at a Pt electrode in concentrated nitric acid solutions, the diffusion coefficients of Ag(I) ion were evaluated to estimate the limiting current density of Ag(II)-mediated electrochemical oxidation (MEO) process, which has been effectively used for the complete destruction of hazardous organic materials. The results showed that, due to the water decomposition reaction which occurred simultaneously with the Ag(I) ion oxidation, background subtractions for the cyclic voltammograms were required to estimate the correct peak currents. The empirical relationship for the diffusion coefficient of Ag(I) was suggested as a function of solution viscosity and temperature.

• Journal of Ocean Engineering and Technology
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• v.21 no.3 s.76
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• pp.65-70
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• 2007

There are many kinds of protection methods for marine structures, with varyingeconomical and environmental advantages. The coating protection method is being widely used in both continental and marine structures. In this study, by adding some additives, such as Zn powder(Zn), carbon black(CB) to epoxy anti-corrosive paint, the effect on the corrosion resistance was investigated throughan electrochemical method. The additive of Zn(20)+CB(10) showed the lowest passivity current density. Polarization resistance in both cyclic voltammogram and impedance measurement of an additive of Zn(20)+CB(10) was also the largest value, compared to other additives. Furthermore, rusting and bubbling was not observed on the surface of the test specimen with the additive of Zn(20)+CB(10), compared to other specimens. It is suggested that the corrosion resistance of the anti-corrosive paint can be improved by using some additives.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2006.11a
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• pp.173-176
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• 2006

There are many kinds of protection methods for marine structures by using and environmental condition. Coating protection method, one of these methods is being widely adopted to both all ground and marine structures. In this study, by adding some additives such as Zn powder(Zn), carbon black(CB) to epoxy anti-corrosive paint, the effect to promote corrosion resistance was investigated with electrochemical method. Corrosion potentials with additives shifted to negative direction than no additive. However passivity current density increased than no additive except for Zn(20)+CB(10), especially, additive of Zn(20)+CB(10) showed the smallest passivity current density. Polarization resistance of Zn(20)+CB(10) by both cyclic voltammogram and impedance measurement was the largest value than other additives. And also surface phenomenon by adding Zn(20)+CB(10) was observed a good add condition not showing bubbling than other additives.