• 한국가스학회지
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• 제5권3호
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• pp.63-72
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• 2001

천연가스 공급용 고압 지하 매설배관에 교류가 유도될 때 쿠폰과 전기저항형 박막센서를 이용하여 교류에 의한 부식속도를 평가하고 주요한 인자를 규명하고자 하였다. 전국에 걸쳐 조사된 교류전압 측정결과를 바탕으로 쿠폰과 전기저항형 박막센서를 설치하고, 주요인자를 고찰하기 위하여 다양한 인자들 (교류전압, 교류전류, 토양 비저항, 주파수, 방식전위)을 정기적으로 기록하였다. 황산동 전극기준 -850mV의 방식전위를 충분히 만족하는 상황에서도 교류에 의한 부식이 진행하였으며, 교류에 의한 부식속도는 교류전압과는 관계없이 교류전류밀도와 주파수에 의존하는 것으로 나타났다. 교류에 의한 부식속도는 유효교류전류밀도에 따라 직선적으로 증가하였으며, 쿠폰에 의한 평가결과 직선의 기울기는 0.619, 전기저항형 센서에 의한 직선의 기울기는 0.885로 나타났다.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 1999년도 춘계학술발표회 초록집
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• pp.19-20
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• 1999

• Corrosion Science and Technology
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• 제14권5호
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• pp.226-231
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• 2015

In spite of highly advanced paint coating techniques, corrosion damage of marine metal and alloys increase more and more due to inherent micro-cracks and porosities in coatings formed during the coating process. Furthermore, flowing seawater conditions promote the breakdown of the protective oxide of the materials introducing more oxygen into marine environments, leading to the acceleration of corrosion. Various corrosion protection methods are available to prevent steel from marine corrosion. Cathodic protection is one of the useful corrosion protection methods by which the potential of the corroded metal is intentionally lowered to an immune state having the advantage of providing additional protection barriers to steel exposed to aqueous corrosion or soil corrosion, in addition to the coating. In the present investigation, the effect of flow velocity was examined for the determination of the optimum corrosion protection current density in cathodic protection as well as the corrosion rate of the steel. It is demonstrated from the result that the material corrosion under dynamic flowing conditions seems more prone to corrosion than under static conditions.

• 한국표면공학회지
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• 제52권2호
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• pp.103-110
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• 2019

As an anti-corrosion method in seawater, cathodic protection is widely recognized as the most effective and technically appropriate corrosion prevention methodology for marine structures against harsh corrosive environment. When applying the cathodic protection in seawater, the surface of the metal facilities the formation of compounds of $CaCO_3$ and $Mg(OH)_2$. These mixed compounds are generally called 'calcareous deposits'. This layer functions as a barrier against the corrosive environment and functions to further inhibit the corrosion process and then leading to a decrease in current demand for cathodic protection. However, calcareous deposit films are partially formed on the surface of the cathode and there are some difficulties to maintain both a corrosion resistance for a long period of time and a strong adhesion between deposits and base metal. In this study, the pulse electrodeposition process was applied to improve adhesion and corrosion resistance of the calcareous deposit films, and to solve the problem of hydrogen embrittlement at high current density. The uniform and compact calcareous deposit films were prepared by pulse electrodeposition process, and their properties were characterized using various surface analytical techniques together with electrochemical methods.

• 한국건축시공학회지
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• 제10권5호
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• pp.21-29
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• 2010

희생양극방식은 지하구조물이나 해양환경하에서 구조물의 방식공법으로 소개되어지고 있다. 1970년대 이후, 희생양극방식이 철근콘크리트 구조물에 적용되어지고 있다. 희생양극방식은 전세계적으로 1990년대 이후 그 유효성을 검증되었다. 그러나, 희생양극방식은 시공적이나 경제적인 약간의 문제점을 가지고 있다. 그 문제점을 해결하기 위하여 고 내구성 금속을 용사시키는 희생양극방식이 개발되었다. 양극재(아연, 알루미늄)를 금속용사로 도포하여 실험체를 제작한 후, 실험체의 부식전류를 측정하여 양극재의 방식성능을 확인하였다. 실험결과 철근 콘크리트 구조물을 대상으로 금속용사를 이용한 희생양극방식이 우수한 방식성능을 가지는 것을 알 수 있었다.

• Journal of Advanced Marine Engineering and Technology
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• 제19권2호
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• pp.47-55
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• 1995

When the low heavy oil is using as fuel oil to the diesel engine, some problems such as corrosion resistance, wear resistance and heat resistance are happened in diesel engine's internal material, especially the adhesive wear of piston ring groove was occurred as a important problem. Therefore to prevent adhesive wear of its groove, the surface of its groove used to be electroplated with Chrominum and for its Chromium electroplating, Fe anode is being used until nowadays because of its Special shape. However in case of using Fe anode, there were some problems such as deterioation of solution, property of Chromium film, and condition of coation. In this paper Pb anode electroplated withPb to the steel plate was investigated for its Chromium electroplating for Pb's high corrosion resistance in acid solution, and Pb anode is not dissolved compared with Fe anode and deterioration degree of solution in case of Pb anode is smaller than that of Fe anode and also property of Chromium film was better than that of Fe anode. Moreover it was known that the optimum cathodic current density for Pb electroplating to steel plate as insoluable anode for Chromium coating of piston ring groove is 30mA/$cm^2$ by experimental results obtained.

• 한국수소및신에너지학회논문집
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• 제16권4호
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• pp.379-385
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• 2005

Effects of Co and Co-P catalysts on the hydrolysis of alkaline $NaBH_4$ solution were investigated. Co and Co-P catalysts were prepared on Cu substrate by electroplating. Hydrogen generation rate of Co-P catalyst was much faster than that of Co catalyst, demonstrating that Co-P had higher intrinsic catalytic activity for the hydrolysis of $NaBH_4$ than Co. Hydrogen generation properties of Co-P catalysts largely depended on cathodic current density and electroplating time because they influenced on the P concentration of the Co-P catalysts. Maximum hydrogen generation rate of Co-P catalyst was 1066 ml/min.g-catalyst in 1 wt.% NaOH + 10 wt.% $NaBH_4$ solution at $20^{\circ}C$, which was obtained at cathodic current density of $0.01\;A/cm^2$ for 130 s.

• Journal of Electrochemical Science and Technology
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• 제11권4호
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• pp.323-329
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• 2020

The cathodic hydrogen evolution ability of different pure metals and their long term galvanic corrosion behavior with pure Mg were investigated. The hydrogen evolution ability of pure Ti, Al, Sn and Zr is weak, while that of Fe, W, Cr, and Co is very strong. Initial polarization test could not completely reveal the cathodic behavior of the tested metals during long term corrosion. The cathodic hydrogen evolution ability may vary significantly in the long term galvanic tests for different metals, especially for Al whose cathodic current density reduced to 1/50 of the initial value. The anodic polarization shows that Al and Sn as alloying elements are supposed to provide relatively good passive effect for Mg alloy, while Ag can provide a slight passive effect and Zn has little passive effect.

• 한국표면공학회지
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• 제49권3호
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• pp.307-315
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• 2016

The properties of AlTiN films by a cathodic arc deposition process have been studied. Oblique angle deposition has been applied to deposit AlTiN films. AlTiN films have been deposited on stainless steel (SUS304) and cemented carbide (WC) at a substrate temperature of $500^{\circ}C$. AlTiN films were analyzed by scanning electron microscopy, glow-discharge light spectroscopy, micro-vickers hardness, and nanoindenter. When applying a current of 50 A to the cathodic arc source, it showed that the density of macroparticle of AlTiN films was 5 lower than other deposition conditions. With the increase of the bias voltage applied to the substrate up to -150 V, the density of macroparticle was decreased. The change of the $N_2$ flow rate during coating process made no influence on the film properties. For the multi-layered films, the film prepared at oblique angle of $60^{\circ}$ showed the highest hardness of 28 GPa and $H^3/E^2$ index of 0.18. AlTiN films have been shown a good oxidation resistance up to $800^{\circ}C$.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2005년도 후기학술대회논문집
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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.