• Corrosion Science and Technology
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• 제20권2호
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• pp.94-104
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• 2021

Atmospheric corrosion severity associated with aircraft parking environment was studied using metallic specimens, and temperature and humidity sensors installed at each aircraft operating base. Data were analyzed after a year of exposure. Silver was used to measure chloride deposition by integrating X-ray photoelectron spectroscopy depth profiles. Carbon steel was utilized to determine the corrosion rate by measuring the weight loss. The time of wetness was determined using temperature and humidity sensor data. Analysis of variance followed by Tukey's "honestly significant difference" test indicated that atmospheric environment inside the shelter varied significantly from that of unsheltered parking environment. The corrosion rate of unsheltered area also varies with the roof. Hierarchical clustering analysis of the measured data was used to classify air bases into groups with similar atmospheric corrosion. Bases where aircraft park at a shelter can be grouped together regardless of geographical location. Unsheltered bases located inland can also be grouped together with sheltered bases as long as the aircraft are parked under the roof. Environmental severity index was estimated using collected data and validated using the measured corrosion rate.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 1998년도 특별강연 및 추계학술발표 개요집
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• pp.288-291
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• 1998

Inconel 600 alloy is used as the material of nuclear steam generator tubing because of its mechanical properties, formability, and corrosion properties. According to reports, the life time of nuclear power plants decreases because of the pitting, intergranular attack, primary water stress corrosion cracking(PWSCC), and intergranular stress corrosion cracking(IGSCC), and denting in the steam generator. The SCC test is very important because of SCC appears in various environment such as solutions, materials, and stress. The C-Rig specimen was made of the steam generator welded sleeve repairing by the pulsed Nd:YAG laser. In the corrosion invironment, corrosion solutions are Primary Water, Caustic, and Sulfate solution and corrosion time is 1624-4877hr. The permitted stress is 30-60ksi.In this C-Ring SCC test is the relationship between corrosion depth, crack and corrosion environment is evaluated. SCC was happens in Sulfate and Corrosion solution but doesn't happen in Primary Water. The corrosion time and stress is very affected by the severely environment of Sulfate or Caustic solution. The microstructure observation indicates that SCC causes interganular failure in the grain boundary of vertical direction.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2000년도 유체기계 연구개발 발표회 논문집
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• pp.373-378
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• 2000

The crevice corrosion of local corrosion occur when the gap exist on metal surface. This crevice corrosion happen to region such as flange of pipe, contact part of casing, under gasket and packing, between valve disk and seat of pump etc. Especially The crevice corrosion of mild steel(SS 400) get serious. This paper was studied on the crevice corrosion of SS 400 in fluid environment. In $0\%,\;2\%,\;3.5\%,\;5\% NaCl$ solution, the aspect of the crevice corrosion and polarization behavior under the crevice corrosion was investigated. And Weight loss rate of SS 400 with crevice and non-crevice was measured according to the NaCl concentration. The main results obtained are as follows : 1) Under crevice corrosion, the corrosion potential become less noble as the concentration of NaCl solution increased. 2) The current density under open circuit potential was high drained as concentration of NaCl solution increased by $3.5\%$ but the concentration increased over $3.5\%$, the current density was low drained. 3) The weight loss rate of SS 400 was increased as concentration of NaCl solution Increased by $3.5\%$, but the concentration increased over $3.5\%$, that of SS 400 was decreased. 4) Effect of oxygen for crevice corrosion in the concentration of $3.5\%$ NaCl solution become sensitive than that $0\%$ NaCl solution.

• Corrosion Science and Technology
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• 제19권2호
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• pp.66-74
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• 2020

In this paper, the author's team has carried out a comparative experimental study on the corrosion characteristics of Q235 steel commonly used in large-scale storage tanks under the specific bottom water environment found with Russian and Daqing crude oil. It was found that there is a certain degree of uniform or local corrosion on the tank floor depending on the kind of bottom water. The bottom water corrosion of Daqing crude oil is a uniform corrosion caused by carbon dioxide. While the Russian crude oil bottom water corrosion is clearly local corrosion caused by co-corrosion of carbon dioxide and hydrogen sulfide, here the corrosion rate is obviously higher than that caused by Daqing crude oil. There are two modes of storage tank inspection and maintenance that have been currently adopted by Chinese refining and chemical enterprises: a regular inspection mode and a API581-2016 risk-based detection mode. These modes have been effectively combined to form an intelligent tank inspection and maintenance mode, software tools to support this intelligent inspection and maintenance management have been developed.

• International Journal of Concrete Structures and Materials
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• 제18권1E호
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• pp.17-22
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• 2006

Artificial cracks were made in the cover concrete of specimens embedding ten types of steel rebars of different Cr contents. The research aims for developing Cr-bearing steel rebars resistant to macrocell corrosion environments induced by cracking in cover concrete. The cracks were subjected to intensive penetration of carbon dioxide (carbonation specimens) to form macrocells. The carbonation specimens were then treated with accelerated corrosion curing, during which current macrocell corrosion density was measured. The corrosion area and loss from corrosion were also measured at the end of 105 cycles of this accelerated curing. The results of the study showed that Cr-bearing steel with Cr content of 5% or more suppressed corrosion in a macrocell corrosion environment induced by the differences in the pH values due to carbonation of cracked parts. Cr-bearing steels with Cr content of 7% or more are proven to possess excellent corrosion resistance.

• Tribology and Lubricants
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• 제19권1호
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• pp.31-35
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• 2003

This paper reports the studies on the wear-corrosion behavior of ductile cast iron in the various pH environments. In the variety of pH solutions, corrosion and wear-corrosion loss of GCD 600 were investigated. Also, the anodic polarization test of GCD 600 using potentiostat/galvanostat was carried out. And rubbed surface of GCD 60 using scanning electron micrographs after immersion and wear-corrosion test was examined in the environment of various pH values. The main results are as following In alkali zone, the wear-corrosion loss of GCD 600 increases, but corrosion loss decreases. The unevenness and crack of wear-corrosion surface in neutral zone becomes duller than that in alkali zone. As the corrosive environment is acidified, wear-corrosion behavior of GCD 600 with passing immersion time becomes sensitive.

• 한국물환경학회지
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• 제33권3호
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• pp.359-369
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• 2017

Water distribution systems supply drinking water to consumers' taps. Internal corrosion of metallic pipe used in drinking water distribution systems has reduced water quality and led to increased levels of toxic heavy metals such as lead, copper and nickel. These problems have been experienced to varying degrees by water utilities in many countries. North America has successfully managed and controlled pipe corrosion and corrosive water in water distribution system based on various policies, regulations and rules. Practical and engineering guidelines for evaluation of pipe corrosion and determination of treatment options are also provided to assist drinking water supplies. In addition, the corrosion mechanism in water distribution systems, such as the complex effects of physical and chemical parameters on the corrosion pipes has been improved to accurately predict corrosion rates of metallic pipes in actual water distribution systems. This paper reviews various regulations, policy statement, and treatment produces on controlling corrosion in drinking water distribution systems in US and Canada and then offers suggestion for management of corrosive water and pipe corrosion in drinking water distribution system in Korea.

• Steel and Composite Structures
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• 제50권3호
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• pp.363-374
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• 2024

The fatigue life of steel wire is affected not only by fatigue load, but also by corrosion environment in service period. Specially, the corrosion pit will lead to stress concentration on the surface of steel wire inducing the formation of fatigue cracks, and the fatigue cracks will accelerate the corrosion process. Therefore, the corrosion fatigue of steel wire is a coupling effect. In this study, the corrosion-fatigue coupling life curve is derived with considering corrosion-fatigue pitting stage, corrosion-fatigue short crack stage and corrosion-fatigue long crack stage. In addition, the stress concentration factors of different corrosion pits are calculated by COMSOL software. Furthermore, the effect of corrosion environment factors, that is, corrosion rate, corrosion pit morphology, frequency and action factor of fatigue load, on fatigue life of steel wire is analyzed. And then, the corrosion-fatigue coupling life curve is compared with the fatigue life curve and fatigue life curve with pre-corrosion. The result showed that the anti-fatigue performance of the steel wire with considering corrosion-fatigue coupling is 68.08% and 41.79% lower than fatigue life curve and fatigue life curve with pre-corrosion. Therefore, the corrosion-fatigue coupling effect should be considered in the design of steel wire.

• 헤리티지:역사와 과학
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• 제53권1호
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• pp.24-33
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• 2020

출토 청동 유물에서는 매장 환경 내 공존하는 복합적인 부식 인자로 인해 다양한 형태와 색상의 부식 생성물이 관찰되며, 이러한 부식 생성물은 장기 부식의 정보뿐만 아니라 보존처리 시 중요한 자료가 될 수 있다. 따라서 청동 유물의 부식층 및 부식 생성물에 대한 과학적 분석을 실시하여 부식층 형성 과정 및 부식 생성물의 특성을 규명하고, 노출된 매장 환경의 특성 및 내부 부식 인자와의 연관성을 해석하는 연구가 필수적이다. 본 연구에서는 동일 유적에서 출토된 청동 유물을 합금비와 제작기법에 따라 분류 후, 표면·부식층·부식 생성물에 대한 종합적인 분석을 실시하여 청동 유물의 부식 메커니즘과 부식층 형성 과정, 부식 생성물의 특성에 대해 알아보고자 하였다. 분석 대상으로 선정된 총 5점의 시료는 합금비 및 제작기법 분석 결과에 따라 2개의 그룹으로 구분되는데, Cu-Sn-Pb합금으로 열처리가 진행되지 않은 Group 1은 내·외측 중 일부 또는 양측에 외부 부식층이 형성되어 있으며, 표면은 녹색 또는 청색으로 확인되었다. 소지 금속에서는 α상, α+δ상 선택 부식이 일어나는 것을 알 수 있었으며, α+δ상 선택 부식 후 빈 공간에 순도가 98% 이상인 Cu가 농축되어 있는 현상이 확인되었다. Cu-Sn합금으로 열처리가 진행된 Group 2는 외부 부식층이 형성되지 않았으며, 표면이 어두운 황색으로 관찰되었다. 또한 Group 1과는 다르게 소지 금속 내부에서 α상 선택 부식이 발생한 것을 확인하였다. 연구결과를 종합해 볼 때 동일한 유적에서 출토된 청동 유물에서도 합금비 및 제작기법에 따라 부식층 형성과정 및 부식 생성물의 형태와 색상, 금속이온 이동경로 등 여러 측면에서 차이를 나타냄을 알 수 있다. 또한 동일 유물에서도 부분적으로 서로 다른 부식 특성을 보이기도 하는데 이는 매장 환경 내 노출 환경에 따라 다른 형태의 부식이 발생할 수 있음을 뜻한다. 따라서 동일 유적에서 출토된 청동 유물이라 하더라도 합금비, 제작기법, 노출 환경에 따라 부식 특성이 다를 것이라고 판단된다. 본 연구는 특정 지역 및 유물을 대상으로 한 부식 특성의 일면을 보여주는 것이므로 향후 여러 지역에서 출토되는 청동 유물의 부식층 및 부식 생성물 특성에 대한 연구를 통해 매장 환경에 따른 부식 메커니즘에 대한 심층적인 연구가 필요할 것으로 판단된다.

• Bulletin of the Korean Chemical Society
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• 제33권5호
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• pp.1566-1570
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• 2012

The combined use of indium and polysorbate 20 (Tween 20) was considered as a new inhibition technique for zinc corrosion. Zn and Zn-In alloy coatings were prepared by electrodeposition and their morphology and composition were characterized by scanning electron microscopy (SEM) and inductively coupled plasma atomic emission spectrometry (ICP-AES). The corrosion inhibition effect of indium and Tween 20 on zinc was investigated by polarization curves and electrochemical impedance spectroscopy (EIS). The corrosion inhibition efficiencies obtained from Tafel and EIS analyses are well in agreement. Zinc corrosion can be inhibited to some extent by the individual use of indium and Tween 20 and higher corrosion inhibition efficiency can be obtained by the combined use of indium and Tween 20.