• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2002년도 총회 및 춘계학술발표회
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• pp.34-37
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• 2002

In this study, electrochemical characteristics variation and removal efficiency with initial pH and mineral compositions during electrokinetic remediation of lead contaminated soils were investigated. Test results showed that heavy metal transportation affected by soil characteristics and electrochemical characteristics varied during electrokinetic remediation. Therefore, in the application of enhanced electrokinetic remediation technique to increase removal efficiency, discrete selection of enhanced technique with characteristics of targeted soil were needed.

• Journal of Advanced Marine Engineering and Technology
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• 제23권5호
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• pp.695-701
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• 1999

Thermal sprayed Ni-Cr alloy coating on the carbon steel was carried out erosion-corrosion test and electrochemical corrosion test in the marine environment. THe erosion-corrosion behavior and electrochemical corrosion characteristics of substrate(SS400) and thermal sprayed Ni-Cr coating was investigated, The erosion-corrosion control efficiency of Ni-Cr coating to substrate was also estimated quantitatively.

• 한국표면공학회지
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• 제30권2호
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• pp.121-127
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• 1997

Vanadium tungsten oxide thin films were formed by RF magnetron sputtering and the effects of tungsten addition on the crystallinity and on the electrochemical behavior were investigated. X-ray analysis revealed that amorphized films could be obtained by tungase addition. In order to investigate the electrochemical behavior of the vanadium tungsten oxide films, electrochemical insertion and extraction of lithium were out in 1m $LiCIO_4$-PC-DME electrolyte using litium metal as a counter electrode. When the tungsten was added to the $V_2O_5$ films, cycling reversibility was considerably improved. Electrochemical test showed the cell capacity of about $70\mu\;Ah/\textrm{cm}^2-\mu\textrm{m}$ when the amount of additive tungseten reached 30 atomic percent. No appreciable degradation of the cell capacity could be observed after hundred cycles of insertion and extration od Li.

• Advances in materials Research
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• 제8권1호
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• pp.37-46
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• 2019

Electrochemical double layer capacitors (EDLCs) which are fabricated using carbon based electrodes have been emerging at an alarming rate to fulfill the energy demand in the present day world. Activated charcoal has been accepted as a very suitable candidate for electrodes but its cost is higher than natural graphite. Present study is about fabrication of EDLCs using composite electrodes with activated charcoal and Sri Lankan natural graphite as well as a gel polymer electrolyte which is identified as a suitable substitute for liquid electrolytes. Electrochemical Impedance Spectroscopy, Cyclic Voltammetry and Galvanostatic Charge Discharge test were done to evaluate the performance of the fabricated EDLCs. Amount of activated charcoal and natural graphite plays a noticeable role on the capacity. 50 graphite : 40 AC : 10 PVdF showed the optimum single electrode specific capacity value of 15 F/g. Capacity is determined by the cycling rate as well as the potential window within which cycling is being done. Continuous cycling resulted an average single electrode specific capacity variation of 48 F/g - 16 F/g. Capacity fading was higher at the beginning. Later, it dropped noticeably. Initial discharge capacity drop under Galvanostatic Charge Discharge test was slightly fast but reached near stable upon continuous charge discharge process. It can be concluded that initially some agitation is required to reach the maturity. However, the results can be considered as encouraging to initiate studies on EDLCs using Sri Lankan natural graphite.

• 한국재료학회지
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• 제17권1호
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• pp.43-49
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• 2007

Electrochemical migration phenomenon is correlated with ionization of anode electrode, and ionization of anode metal has similar mechanism with corrosion phenomenon. In this work, in-situ water drop test and evaluation of corrosion characteristics for SnPb solder alloys in $Na_2SO_4$ solutions were carried out to understand the fundamental electrochemical migration characteristics and to correlate each other. It was revealed that electrochemical migration behavior of SnPb solder alloys was closely related to the corrosion characteristics, and Sn Ivas primarily ionized in ${SO_4}{^2-}$ solutions. The quality of passive film formed at film surface seems to be critical not only for corrosion resistance but also for electrochemical migration resistance of solder alloys.

• Journal of Electrochemical Science and Technology
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• 제1권1호
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• pp.63-68
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• 2010

The $Li_4Ti_5O_{12}$/AC composite was prepared by sol-gel process with ultrasonication. The prepared composite was characterized by SEM, XRD and TG analysis, and their electrochemical behaviors were investigated by cyclic voltammetry, electrochemical impedance spectroscopy and charge-discharge test in 1M $LiBF_4$/PC electrolyte. From the results, the $Li_4Ti_5O_{12}$ particles coated on AC surface had an average particle size of 100 nm and showed spinel-framework structure. When the potential range of the $Li_4Ti_5O_{12}$/AC composite was extended from 0.1 to 2.5 V, redox peaks and electric double layer property were revealed. The initial discharge capacity of $Li_4Ti_5O_{12}$/AC composite was 218 mAh $g^{-1}$ at 1 C. The enhancement of discharge capacity was attributed to electric double layer of added activated carbon.

• Journal of Electrochemical Science and Technology
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• 제14권2호
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• pp.131-138
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• 2023

The carbon felt is usually hired as electrodes for vanadium redox flow battery (VRFB). In the study, surface modification of carbon felt under CO₂ atmosphere with variables of operating various temperature ranges between 700℃ and 900℃. The qualitative and quantitative analysis were carried out such as scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS) to observe degree of surface modification. Result of XPS analysis confirmed increase of carbon and oxidation functional group on the surface with increase of temperature. SEM image was discovered similar phenomena. Electrochemical characteristics such as cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) revealed the improved electrode performance with increase of temperature. However, the electrochemical performance under treatments temperature of 900℃ was less than that of under treatment temperature of 850℃ due to weight loss at the treatment temperature of 900℃. From the CV and EIS results, the best electrochemical characteristics was at the temperature of 850℃. That of at the temperature of 900℃ was decreased due to weight loss. The energy efficiencies (EE) obtained from full cell test were 69.37, 80.76, 82.45, and 75.47%, at the temperature of 700, 800, 850, and 900℃, respectively.

• Journal of Electrochemical Science and Technology
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• 제15권2호
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• pp.220-241
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• 2024

Due to its unique advantages, electrochemical machining (ECM) is playing an increasingly significant role in the manufacture of difficult-to-machine materials. Most of the current ECM research is conducted at room temperature, with studies on ECM in a cryogenic environment not having been reported to date. This study is focused on the electrochemical dissolution characteristics of typical iron and nickel base alloys in NaNO₃ solution at low temperature (-10℃). The polarization behaviors and passive film properties were studied by various electrochemical test methods. The results indicated that a higher voltage is required for decomposition and more pronounced pitting of their structures occurs in the passive zone in a cryogenic environment. A more in-depth study of the composition and structure of the passive films by X-ray photoelectron spectroscopy and electrochemical impedance spectroscopy showed that the passive films of the alloys are modified at low temperature, and their capacitance characteristics are more prominent, which makes corrosion of the alloys more likely to occur uniformly. These modified passive films have a huge impact on the surface morphologies of the alloys, with non-uniform corrosion suppressed and an improvement in their surface finish, indicating that lowering the temperature improves the localization of ECM. Together with the cryogenic impact of electron energy state compression, the accuracy of ECM can be further improved.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2002년도 Proceedings of the International Welding/Joining Conference-Korea
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• pp.273-275
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• 2002

The effect of post-weld heat treatment (PWHT) of marine structures steel was investigated at electrochemical viewpoint. In addition, slow strain rate test (SSRT) was carried out to investigate both electrochemical and mechanical properties by PWHT effect during impressed current cathodic protection. The optimum cathodic protection potential by SSRT was -770 mV(SCE). At the applied cathodic protection potential of -770 mV -850 mV(SCE), the fracture morphology was dimple pattern with ductile fracture, while it was transgranular pattern (Q.C: quasi cleavage) under -875 mV(SCE).

• Corrosion Science and Technology
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• 제5권1호
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• pp.15-22
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• 2006

The introduction of two-grid inside a conventional process system produces a reactive coating deposition and increases metal ion ratio in the plasma, resulting in denser and smoother films. The corrosion behaviors of TiN coatings were investigated by electrochemical methods, such as potentiodynamic polarization test and electrochemical impedance spectroscopy (EIS) in deaerated 3.5% NaCl solution. Electrochemical tests were used to evaluate the effect of microstructure on the corrosion behavior of TiN coatings exposed to a corrosive environment. The crystal structure of the coatings was examined by X-ray diffractometry (XRD) and the microstructure of the coatings was investigated by scanning electron microscopy (SEM) and transmission electron spectroscopy (TEM). In the potentiodynamic polarization test and EIS measurement, the corrosion current density of TiN deposited by two grid-attached magnetron sputtering was lower than TiN deposited by conventional magnetron type and also presented higher Rct values during 240 h immersion time. It is attributed to the formation of a dense microstructure, which promotes the compactness of coatings and yields lower porosity.