• Corrosion Science and Technology
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• v.7 no.5
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• pp.296-299
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• 2008

High order statistical parameters were evaluated using the electrochemical noise data collected during corrosion of type 430 stainless steel coupled to a inert, platinum electrode in 3.5% NaCl solution. High order statistical parameters are shown to predict uniform corrosion properly. However, Localization index, skewness of current, kurtosis and skewness of potential are capable of predicting pitting corrosion only when the transients are large with long life time. Of the high order statistical parameters evaluated, kurtosis of current is found to be the most sensitive parameter for detecting uniform and pitting corrosion.

• Journal of Electrochemical Science and Technology
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• v.11 no.4
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• pp.346-351
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• 2020

The removal characteristics of copper (Cu) from electrochemical surface by voltage-activated reaction were reviewed to assess the applicability of electrochemical-mechanical polishing (ECMP) process in three types of electrolytes, such as HNO₃, KNO₃ and NaNO₃. Electrochemical surface conditions such as active, passive, transient and trans-passive states were monitored from its current-voltage (I-V) characteristic curves obtained by linear sweep voltammetry (LSV) method. In addition, the oxidation and reduction process of the Cu surface by repetitive input of positive and negative voltages were evaluated from the I-V curve obtained using the cyclic voltammetry (CV) method. Finally, the X-ray diffraction (XRD) patterns and energy dispersive spectroscopy (EDS) analyses were used to observe the structural surface states of a Cu electrode. The electrochemical analyses proposed in this study will help to accurately control the material removal rate (MRR) from the actual ECMP process because they are a good methodology for predicting optimal electrochemical process parameters such as current density, operating voltage, and operating time before performing the ECMP process.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1844-1847
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• 2003

Electrochemical micro-machining(EMM) is used to achieve a desired workpiece surface by dissolving the metal workpiece with an electrochemical reaction. This machining method can be applied to metal that is difficult to machining using other methods. The workpiece dissolves when it is positioned close to the tool electrode in electrolyte and current is applied. This aim of this work is to develop electrochemical micro-machining(EMM) technique for micro groove shape by establishing appropriate electrochemical parameters of machining

• Journal of the Korean Electrochemical Society
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• v.7 no.2
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• pp.80-82
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• 2004

The a.c. technique is employed to evaluate electrochemical characteristics of Naphthalie-1,4,5,8-tetracarboxylic acid bisanilide (NTB). The measurements were carried out in dry and pure propionitrle (PCN) and acetonitrile(CAN) at the hanging mercury drop electrode [HMDE). An A.C. phase sensitive detector using computer controlled lock-in amplifier was employed. Primary goal of this report, was to establish on a firm the rare behavior of the phase angle associated with a.c. polarograms of the compound. Although, not an initial goal of this study, the electron transfer rate parameters attending the electroreduction of the compound under investigation were determined. This because the results shed some light on the electrokinetics in aprotic solvent which until recently negligible data were available. Experimental Results and comparison of data obtained are reported. The good precision of the method makes it suitable for studying electrochemical data with unusual behavior at electrodes in non aqueous media.

• Journal of the Korean Chemical Society
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• v.54 no.1
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• pp.13-22
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• 2010

The photophysical properties of 7-diethylaminocoumarin (DEAC) laser dye have been measured in different solvents. The emission spectrum of DEAC has also been measured in cationic (CTAC) and anionic (SDS) micelles. The laser parameters have been calculated in different solvents namely acetone, dioxane, ethanol and dimethylforamide(DMF). The photoreactivity of DEAC has been studied in $CCl_4$ solvent using 366 nm light. The values of photochemical yield (${\Phi}_c$) and rate constant (k) are determined. The interaction of organic acceptors such as picric acid (PA), tetracyanoethylene (TCNE) and 7,7,8,8-tetracynoquinonedimethane (TCNQ) with DEAC are also studied using fluorescence measurements in acetonitrile ($CH_3CN$). The electrochemical investigation of (DEAC) has been carried out using cyclic voltammetry and convolutive voltammetry combined with digital simulation technique at a platinum electrode in 0.1 mol $L^{-1}$ tetrabutyl ammonium perchlorate (TBAP) in $CH_3CN$ solvent. The electrochemical parameters of the investigated compound were determined using cyclic and convolutive voltammetry. The extracted electrochemical parameters were verified and confirmed via digital simulation method.

• Journal of Electrochemical Science and Technology
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• v.12 no.3
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• pp.365-376
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• 2021

Two arylamino substituted mercaptoimidazole derivatives namely 4,5-dimethyl-1-(phenylamino)-1H-imidazole-2(3H)-thione (I1) and 4,5- dimethyl-1-((p-chlorophenyl)amino)- 1H-imidazole-2(3H)-thione (I2) were synthesized and investigated as corrosion inhibitors for carbon steel in 0.5 M HCl solution by means of electrochemical impedance spectroscopy (EIS), potentiodynamic polarization, ATR-FTIR spectroscopy and SEM. The results showed that the investigated mercaptoimidazole derivatives act as mixed type inhibitors and inhibition efficiency follows the I2>I1 order. Adsorption of inhibitors on metal surface was found to obey the Langmuir adsorption isotherm. Thermodynamic parameters revealed that adsorption of the inhibitors has both physisorption and chemisorption adsorption mechanism. Electrochemical test results were supported by quantum chemical parameters obtained from DFT calculations.

• Nuclear Engineering and Technology
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• v.41 no.10
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• pp.1315-1322
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• 2009

The present article is concerned with the application of an electrochemical noise (EN) monitoring technique to analyze the initiation and propagation of Pb-assisted stress corrosion cracking (SCC) of an Alloy 600 material in a simulated environment of a steam generator (SG) sludge pile at high temperatures. A typical increase of electrochemical current noise (ECN) and electrochemical potential noise (EPN) was frequently recorded from the EN measurement in a caustic solution with such impurities as PbO and CuO, indicating that there are localized corrosion events occurring. With the aid of microscopic and spectral analyses, the EN data involving information on such stochastic processes as uniform corrosion and the initiation and propagation of SCC, were analyzed based on a stochastic theory.

• Journal of Electrochemical Science and Technology
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• v.9 no.2
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• pp.149-156
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• 2018

In this technical note, I report the analysis of electrochemical impedance data measured with potential sweeping. Even though the instruments for voltammetric impedance measurements have been developed for decades using different approaches, their applications are limited due to the lack of well-established protocols to easily analyze voltammetry data. To fill this gap, the singular point of the specific potential is considered that is only determined by the standard/formal potential and the transfer coefficient and is independent of the kinetics and experimental parameters (including revertability) of faradaic reactions. Taking the advantage of its inertness, I suggest an approach employing the singular point as a reference to obtain general electrochemical information. As all the concepts and methods are verified with numerical simulations, this technique is expected to be applied for complex reactions involving electrochemical and chemical reaction mechanisms.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1277-1281
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• 2007

A Nano-tip as a cold field emitter for inducing a field emission current has manufactured in many ways. In the paper, the electrochemical etching method is used. Thus, in order to optimize the final shape as the field emitter, the reliable fabrication system for electrochemical etching was constructed. In addition, the effective parameters such as applied voltage, submerged length, meniscus height, electrolyte concentration and environmental condition(vibration, humidity, cut-off time) have investigated in detail. By controlling the parameters, reliable tungsten tip for field emitter was fabricated. And the fabricated tungsten tip was evaluated optically. Finally, the very sharp apex of the tungsten tip was observed with scanning electron microscope.

• Textile Coloration and Finishing
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• v.17 no.4 s.83
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• pp.1-6
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• 2005

We studied the degree of variety of indigo for the electrochemical redox reaction in addition of reducing agent and the electrokinetic parameters. The electrokinetic parameters such asthe number of electron and the exchange rate constant were obtained by cyclic voltammetry. With increasing scan rate, the reduction currents of indigo were increased and the reduction potentials were shifted to the negative direction. As the results, the reduction processes of the indigo were proceeding to totally irreversible and diffusion controlled reaction. Also, exchange rate constant ($k^0$) and diffusion coefficient ($D_0$) of indigo were decreased by increasing concentration of reducing agent. We found that the less concentration, the more easily diffused and electron transferred and the product was more stable.