• Corrosion Science and Technology
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• 제17권4호
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• pp.166-175
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• 2018

In this study, the electrochemical properties of CP-Ti (commercially pure titanium) and Ti-64 (Ti-6Al-4V) were evaluated and the effect of hydrofluoric acid on corrosion resistance and electrochemical properties was elucidated. Additive manufactured materials were made by DMT (Directed Metal Tooling) method. Samples were heat-treated for 1 hour at $760^{\circ}C$ and then air cooled. Surface morphologies were studied by optical microscope and SEM. Electrochemical properties were evaluated by anodic polarization method and AC-impedance measurement. The oxide film formed on the surface was analyzed using an XPS. The addition of HF led to an increase in the passive current density and critical current density and decreased the polarization resistance regardless of the alloys employed. Based on the composition of the oxide film, the compositional difference observed by the addition of HF was little, regardless of the nature of alloys. The Warburg impedance obtained by AC-impedance measurement indicates the dissolution of the constituents of CP-Ti and Ti-64 through a porous oxide film.

• 한국표면공학회지
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• 제51권5호
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• pp.316-324
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• 2018

Harsh seawater environment is subdivided into marine atmosphere, splash zone, tidal zone, submerged zone and bottom of sea depending on the exposed part. Since corrosion rate depends on the conditions of the exposed parts, proper protection and maintenance for each parts are essential for long-term use of steel structures in seawater environment. For steel structures which were installed in Shiwha Lake, a special maintenance system is required to guarantee its long-term durability and safety. As the tidal power plant has recently been operated, the salinity has risen due to the rapid influx of seawater upstream into Sihwa Lake and the corrosion tendency of the structure is variable according to the water level fluctuation. In this study, corrosion properties of steel structures under water level fluctuation was evaluated by corrosion rate measurement, visual inspection and natural potential measurement and their durability and life management were discussed in view of the effect of variation in of seawater level fluctuations in Shihwa Lake.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 추계학술대회 논문집 학회본부 B
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• pp.355-357
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• 2000

Measurement used electricsal sounding(MacOHM 2115, Japan) for grounding resistance of Jung-Bu highway Ha-Nam IC about 500m. To applied measurement method is fall of potential method and analysis earth resistivity used ESII(Electrical Sounding Interactive Interpretation) program. This result propose for construction plan of electric corrosion.

• Corrosion Science and Technology
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• 제6권3호
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• pp.140-146
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• 2007

In the paper, with corrosion velocity measurement and metallographic observation on specimens after sulfuric acid/ferric sulfate boiling experiment, intergranular corrosion tendency of the new type ultra low carbon stainless steel developed by ourselves which experienced solution treatment at different temperatures was evaluated. A VHX 500 super depth field tridimensional microscope was used to observe corrosion patterns on the sample surfaces. The depth and width of grain boundary corrosion groove were measured by the tridimensional microscope, which indicated that the corrosion degrees of the samples which received solution treatment at different temperatures are quite different. Transgranular corrosion at different degree occurred along with forged glide lines. After comparison it was proved that the stainless steel treated at $1100^{\circ}C$ performs very well against intergranular corrosion.

• 한국구조물진단유지관리공학회 논문집
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• 제14권6호
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• pp.179-187
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• 2010

콘크리트 내부에 매설된 철근의 부식은 철근콘크리트구조물의 조기 성능저하와 붕괴의 주요원인이 되고 있다. 철근콘크리트 구조물에 발생하는 열화현상 중에서 철근부식에 의해 발생되는 염해는 그 피해가 다른 열화 현상보다 심하고 구조물의 보수 및 시공 측면에서도 막대한 경비가 요구되고 보수시기 또한 정하기 힘들다. 따라서 철근의 부식상태에 대한 조기발견은 관리자의 효율적인 보수 및 보강계획 수립을 위해 매우 중요하다. 한편 철근 부식을 평가하는 방법 중 비파괴측정이 많이 사용되고 있다. 특히 CM-II(corrosion meter) 측정기는 자연전위와 분극저항 및 콘크리트 비저항을 측정할 수 있어서 많이 사용되지만 몇 가지 단점을 가지고 있다. 이러한 단점을 극복하기 위해 매립형 미니센서가 개발되어져 왔다. 이 미니센서를 이용하여 철근 부식을 측정한 후 CM-II(corrosion meter)의 측정결과와 비교분석하여 개발된 미니센서의 타당성을 검증하였다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1997년도 가을 학술발표회 논문집
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• pp.275-280
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• 1997

An experimental study to evaluate corrosion protection systems was undertaken with 47 reinforced concrete slab specimens subjected to cyclic wet and dry saltwater exposure. Corrosion measurements included monitoring marcrocell corrosion currents, which are generally accepted in United States practice. Test results indicate that specimens containing 2 kg/$\textrm{m}^3$ of NaCl an exposed to a 10 percent of NaCl show high values of corrosion currents. For the specimens with water repellent membrane currents kept relatively low numerical values, while test specimens with surface corrosion inhibitor hyprotective systems show high values of corrosion currents. No clear indication of the corrosion inhibitor protective systems might be due to the extremely high chloride exposure of the specimens, which has brought the accelerated corrosion. It would be expected that evaluation of the corrosion protective systems need long-term measurement with specimen exposed les chloride but simulating the real condition.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1997년도 봄 학술발표회 논문집
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• pp.203-209
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• 1997

An experimental study to evaluate to evaluate corrosion protection systems was undertaken with 44 reinforced concrete slab specimens subjected to cyclic wet and dry saltwater exposure. Corrosion measurements included monitoring macrocell corrosion currents, which are genrerally accecpted in United States practice. Test results indicate that specimens containing 2 kg/$\textrm{m}^3$ of NaCl and exposed to wet(outdoor) and dry(indoor) conditions but not to saltwater show very low values of corrosion measurements regardless applying any corrosion protective systems. Corrosion currents of the specimens exposed at 10 percent of NaCl were higher than that of the specimen exposed at 5 percent of NaCl, so the density of the salt water had an influential effect on the test. For the specimens with water repellent membrane currents kept relatively low numerical values, but test specimens with surface corrosion inhibitor protective system showed high values of corrosion current. It would be expected that evaluation of the corrosion protective systems need long-term measurement.

• Corrosion Science and Technology
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• 제17권2호
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• pp.54-59
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• 2018

The effect of external DC electric field on atmospheric corrosion behavior of zinc under a thin electrolyte layer (TEL) was investigated by measuring open circuit potential (OCP), cathodic polarization curve, and electrochemical impedance spectroscopy (EIS). Results of OCP vs. time curves indicated that the application of external DC electric field resulted in a negative shift of OCP of zinc. Results of cathodic polarization curves measurement and EIS measurement showed that the reduction current of oxygen increased while charge transfer resistance ($R_{ct}$) decreased under the external DC electric field. Variation of OCP negative shift, reduction current of oxygen, and $R_{ct}$ increase with increasing of external DC electric field strength as well as the effect of external DC electric field on double-layer structure in the electrode/electrolyte interface and ions distribution in thin electrolyte layer were analyzed. All results showed that the external DC electric field could accelerate the corrosion of zinc under a thin electrolyte layer.

• 전기화학회지
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• 제10권3호
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• pp.179-183
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• 2007

The corrosion behavior of metal covered with mortar under a wet-dry cyclic condition were investigated to apply for the measurement of corrosion rates of reinforcing steel in concrete structure. The carbon steel in mortar having t=3 mm cover thickness was exposed to the alternate condition of 6 h immersion in chloride containing solution and 18 h drying at $25^{\circ}C$ and 50%RH. The electrochemical phenomena of a carbon steel and mortar interface was explained by an equivalent circuit consisting of a solution resistance, a charge transfer resistance and a CPE(Constant Phase Element). The corrosion rates were monitored continuously during exposure using an AC impedance technique. Simultaneously, the current distribution over the working electrode during impedance measurement was analyzed from the phase shift, $\theta$, in an intermediate frequency. The result showed that corrosion rate monitoring using an AC impedance method is suitable under the given exposure conditions even during the drying period when the metal is covered with the wetted mortar.

• 전기학회논문지
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• 제62권2호
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• pp.239-245
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• 2013

In this paper, we propose a time-frequency domain reflectometry (TFDR) based measurement method for localizing concentric neutrals corrosion on live underground power cable. It consists of two inductive couplers which can transmit the reference signal into live underground power cable and measure the reflected signals from the impedance discontinuities of concentric neutrals corrosion. In order to compensate the dispersion of the measured reflected signal via inductive coupler, an equalizer based on Wiener filtering is designed. To improve the localizing performance of concentric neutrals corrosion in the vicinity of the measurement point, the reference signal is removed from the measured reflected signals. The localization performance of the proposed method is verified by the concentric neutrals corrosion localization experiment.