• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.38 no.4
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• pp.265-270
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• 2002

Most of all the mechanical devices are becoming more high-speed and high-power as well as their used condition being more pollution with rapid development in industrial part. So, it is necessary for these devices to equip cooling system to overcome that kind of severe using condition. Industrial development and income increase causes rapid increase in using fossilenergy and it results in accelerating environmental pollution owing to the increasement in emission of air pollution substance. Specially, fresh water like stream and river water is acidified. Therefore, corrosion damage is accelerated in radiator for automobile that is using acidified water. So, in this study, corrosion test was carried out in distilled and tap water for the investigation on the corrosion behavior of Al-alloy that is using as material for radiator of automobile The main results obtained are as follows According to increase of temperature, open circuit potential is decreased in fresh water. And open circuit potential after deaeration is lower than that before deaeration. Corrosion current density in distilled water is less drained than that of tap water. And Corrosion current density after deaeration is less drained than that before deaeration.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.37 no.1
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• pp.65-70
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• 2001

As consumption rate of energy increase rapidly, the facilities of fuel storage tank become large size. Almost all of the industry or public facilities storing fuel in underground fuel storage tank is manufactured by steel materials. Thus, this fuel storage tank made of steel materials is damaged by stray-current corrosion, it become destruction. If fuel storage tank is destructed, petroleum, oil and gas are leaked. So it bring about environmental pollution, energy loss, fire and explosion. Therefor, in this study, for study on the prevention of corrosion damage in underground fuel storage tank, it were investigated by corrosion and stray-current corrosion for SS 400 in dry sea sand and wet sea sand along to specific resistance. The main results obtained are as follows : As specific resistance decrease in wet sea sand, corrosion rate per year increase linearly, in case of back fill up wet sea sand in underground fuel storage tank, if the water is flow into dry sea sand, corrosion tendency of underground fuel storage tank is supposed sensitive.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2015.11a
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• pp.321-321
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• 2015

해수 환경에 노출된 대부분의 금속재료는 직 간접적으로 부식의 영향을 받는다. 이와 같이 해수에 침지된 금속재료의 부식 방지에는 음극방식법이 주로 사용되고 있다. 과거의 음극방식 설계에는 양극 크기와 방식전류 밀도, 소모율 등 양극 자체에 대한 변수만이 고려되었으나, 20여 년 전부터는 해수 오염도, 수온 및 유속 등을 종합적으로 고려하여 설계하고 있다. 특히 대부분의 금속은 부식성 환경에서 생성된 부동태 피막이 해수 유동에 의해 파괴되면서 급속히 손상된다. 따라서 본 연구에서는 해수 특성을 고려한 최적의 소요방식전류밀도 선정을 위해 전기화학실험을 실시하였다. 실험 결과, 해수 온도 상승에 따라 확산속도가 빨라져 최적 방식 전류밀도가 증가하는 경향을 나타냈다.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.39 no.3
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• pp.211-217
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• 2003

Recently, with rapid development in marine and shipbuilding industries such as marine structures, ships and chemical plants for ship, there occurs much interest in the study on corrosion characteristics played an important role in mechanical design. This paper was studies on the corrosion characteristics of chromium plating in the marine environment. Under the various specific resistance, the electrochemical polarization test of chromium plating was carried out. And thus corrosion potential, polarization resistance, corrosion current density, control efficiency of corrosion and polarization control behavior of chromium plating are investigated. The main results are as the followed : 1. The polarization resistance of Cr plating and Ni become higher than that of base metal, also and these material become low with decrease of the specific resistance. 2. As the specific resistance decreases, the corrosion current density of Cr and Ni plating is lower than that of base metal. 3. The corrosion reaction of Cr plating, Ni plating and base metal vs. specific resistance is cathodic control.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.11b
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• pp.475-480
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• 1996

Alloy 600 및 Alloy 690의 Caustic 분위기에서, 시편의 포텐셜을 재료의 anodic polarization curve의 active-passive transition 영역의 한 값으로 일정하게 유지함으로서 응력부식균열을 쉽게 유발시키는 정전위 시험방법을 사용하여, 두 합금의 부식저항성을 비교하였다. C-ring형태의 Alloy 600 및 690 시편에 응력을 부과하고 30$0^{\circ}C$의 10% NaOH용액에서 7일간 정전위 응력부식시험을 수행하였다. Alloy 600의 경우, 입계를 따르는 100$\mu$m정도 깊이의 균열이 발생하였으나 Alloy 690의 경우는 균열이 유발되지 않았다. Alloy 690의 경우 부식 시험시간이 경과함에 따라 표면부식전류밀도는 주기적인 Passivation 경향을 보이나 Alloy 600의 경우는 점진적으로 표면부식전류밀도가 증가한다. Alloy 690의 강한 응력부식저항성은 이와 같은 주기적인 Passivation에 의한 것으로 판단된다.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05c
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• pp.335-340
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• 1996

핵융합로 제1벽 재료의 후보재로 고려되는 Fe-Cr-Mn계 스테인리스강을 진공 용해하여 이 합금의 미세 조직 및 기계적 성질 그리고 부식 특성에 미치는 Mn, W의 첨가 효과 및 소둔 열처리 온도의 효과에 대하여 실험하였다. 미세 조직 분석은 광학 현미경 관찰, XRD분석 등으로 행하였으며, 기계적 시험으로는 상온 인장 시험, 경도 시험 및 충격 시험을 행하였다. 그리고 부식 시험으로는 부식 환경을 염산과 황산으로 나누어 각 환경에서의 양극 분극 시험을 행하였다. Mn함량이 증가할수록 오스테나이트상이 증가하고 있으나, $\alpha$'마르텐사이트는 급격히 감소하는 대신$\varepsilon$마르텐사이트는 Mn함량이 20%일 때 최대간을 보인 뒤 감소하고 있다. Mn함량이 증가할 수록 또한 소둔 온도가 상승할수록 항복 강도, 인장 강도 및 경도는 감소하였으며 연신율은 증가하였다. 이러한 결과는 합금 중의 오스테나이트 및 마르텐사이트 조직의 함량과 밀접한 관련이 있는 것으로 판단된다. 한편 합금 중의 Mn함량이 증가할수록 부식 환경에 관계없이 부식 저항성의 변화는 크지 않은 것으로 나타났다. 그러나 W함량이 증가하면 환경에 관계없이 임계 전류 밀도를 감소시키나, 부동태 전류 밀도는 HCI환경에서는 감소시키고 H$_2$SO$_4$환경에서는 오히려 증가시키는 상반된 효과가 나타났다.

• Journal of Radiation Protection and Research
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• v.31 no.2
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• pp.105-113
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• 2006

The oxidizing species are generated from the radiolysis of groundwater in the pore of buffer material around the canister used for the disposal of spent fuels. A mathematical model was introduced to calculate the cathodic current density induced by the oxidant around the canister, which determined the corrosion of carbon steel. An analytical solution was derived to get the cathodic current density in the cylindrical coordinate. The cathodic current densities from both the rectangular coordinate and cylindrical coordinate were compared with each other. The source terms and absorbed dose rate for the calculation of the radiolysis were calculated using the ORIGEN2 and MCNP computer code, respectively. The radius of the canister was determined with the new model in order to prevent the local corrosion. The results showed that the new solution made the cathodic current density around 25 % lower than the Marsh model.

• Proceedings of the Korean Nuclear Society Conference
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• 1995.05b
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• pp.597-602
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• 1995

원자력 발전소 증기발생기 전열관 재료인 합금 600의 대체재료로써 설계된 합금 690의 내식성의 향상을 위해서 염소 이온이 다량 포함된 환경에서의 부식 저항성을 크게 향상시킨다고 보고된 Mo을 첨가하여 부식 및 기계적 특성에 미치는 영향을 알아보았다. 미세조직상 Mo를 첨가함에 따라 기지에 미세한 석출물이 석출되어 입자의 미세화를 얻을 수 있었으며 연신율의 감소없이 항복 강도, 인장 강도 및 경도의 향상을 얻을 수 있었다. 공식 저항성은 Mo의 첨가량이 증가함에 따라 부식 속도가 감소하였다. 양극 분극 시험에서도 5$0^{\circ}C$, 3.5wt% NaCl 용액과 0.5N HCl 용액 모두에서 Mo의 함량이 증가할수록 부동태화 전류 밀도 및 임계 부동태화 전류 밀도가 감소하여 전반적으로 현저한 내식성의 향상을 관찰할 수 있었다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.6
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• pp.1-13
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• 2022

This study aims to investigate the feasibility of the half-cell potential (HCP) measurements on the concrete surface for evaluation of corrosion rate (or corrosion levels) of reinforcing steel in concrete. A series of experimental study is performed to measure HCP (or corrosion potential, E_corr) and corrosion current density (i_corr) of reinforcing steel in concrete cube specimens, with a side length of 200 mm. Various corrosion levels in a range of 0% to 20% of the test specimens are accelerated by impressing current to the reinforcing steel in concrete immersed in 3.0 % NaCl solution. HCP is measured in accordance with ASTM C876-15, and corrosion current density is determined by using the Stern-Geary equation and measured polarization resistance measured by electrochemical impedance spectroscopy (EIS). As a result, a numerical formula that relates HCP and i_corr in the test specimen is established by a regression analysis of the measured data in this study. It is observed that HCP is linearly correlated with log(i_corr) with a R² greater than 0.87, which is less affected by the experimental variables such as concrete mixture proportion, diameter of reinforcing steel and the amount of applied current in this study. These results exhibit that HCP measurements could be effective for evaluation of corrosion rate (or corrosion levels) of reinforcing steel in concrete in the case of exposed to a certain consistent environment.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.37 no.2
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• pp.147-152
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• 2001

Corrosion damage of boiler, factory equipment and so forth occur quickly due to using of the polluted water, resulting in increasing leak accident. Especially, working life of hot water boiler using the polluted water becomes more short, and energy loss increases. The cathodic protection method is the most economical and reliable one to prevent corrosion damage of steel structures. Mg-base alloys galvanic anode protection of cathodic protection methode is suitable for the application of hot water boiler using water with high specific resistance such as tap water. This paper is studied on the cathodic protection characteristics of hot water boiler. In tap water solution, the measurement of cathodic protection potential according to the time elapsed is carried out, and behavior of cathodic polarization with current change is investigated. The main results obtained are as follows. In hot water boiler shell, the open circuit potential of base metal become less noble than that of weld Bone, and the current density of base metal becomes low than that of weld zone. The further distance from Mg-alloy galvanic anode, the higher cathodic protection potential of hot water boiler appears. And protective potential becomes high according to pass cathodic protection time and after 6∼10 days become stable.