• Corrosion Science and Technology
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• 제18권6호
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• pp.243-252
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• 2019

The pitting corrosion and inhibition studies of AZ31B magnesium alloy were investigated in the alkaline solution (pH12) with chloride and inhibitors. The corrosion behavior of passive film with/without Cl^- in the alkaline electrolyte were conducted by polarization curve and immersion tests in the presence of various additives (inhibitors) to clarify the inhibition efficiency of pitting corrosion at higher potential region. Critical concentration of pitting corrosion for Mg alloy was evaluated with 0.005 M NaCl in 0.01 M NaOH on the anodic polarization behavior. Critical pitting of AZ31B Mg alloy in 0.01 M NaOH is a function of chlorides; E_pit = - 1.36 - 0.2 log [Cl^-]. When the Sodium Benzoate (SB) was only used as an inhibitor, a few metastable pits developed on the Mg surface by an immersion test despite no pitting corrosion on the polarization curve meaning that adsorption of SB on the surface is insufficient protection from pitting corrosion in the presence of chloride. The role of SB and Sodium Dodecylbenzenesulfonate (SDBS) inhibitors for the Mg alloy surface in the presence of chloride was suppressed from pitting corrosion to co-adsorb on the Mg alloy surface with strong formation of passive film preventing pitting corrosion.

• 한국표면공학회지
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• 제37권2호
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• pp.110-118
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• 2004

The corrosion of pure titanium (CP- Ti Grade 2) and titanium alloy (Ti6Al4V ELI) were studied under various conditions of simulated body fluids. The static immersion test and the electrochemical test were performed in accordance with ISO 10271 : 2001. For the electrochemical test, the open circuit potential was monitored as a function of time, and the cyclic polarization curve was recorded. The corrosion resistance was evaluated from the values of corrosion potential, passivation current density, breakdown potential, and the shape of hysteresis etc. The effects of alloy type, surface condition, temperature, oxygen, and constituents in the fluids such as acid, chloride were estimated. Both specimens had extremely low dissolution rate in the static immersion test. They showed strong passivation characteristics in the electrochemical test. They maintained negligible current density throughout the wide anodic potential range. The passive layer was not broken up to 2.0 V (vs. SCE). The hysteresis and the shift of passivation potential toward the anodic direction was observed during the reversed scan. The passivation process appeared to be accelerated by oxygen in air or that dissolved in the fluids. The passivation also proceeded without oxygen by the reaction of constituents in the fluids. Acid or chloride in the fluids, specially later weakened the passive layer, and then induced higher passivation current density and less shift of passivation potential in the reversed scan. CP-Ti Grade 2 was more reactive than Ti6Al4V ELI in the fluids containing acid or chloride, but thicker layer produced on its surface provided higher corrosion resistance.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2013년도 춘계 학술논문 발표대회
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• pp.98-99
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• 2013

The amount of surface chlorides of architectural structure in incoming salt environment depends on the characteristics of distribution of incoming salt in atmosphere. Therefore, many researches are being conducted on deducting the correlation between incoming salt amount attached to the surface of real structure and that of atmosphere after quantitative measurement. However, in real environment, these studies are somewhat far fetched. That is because incoming salt in atmosphere are changed by various climatic conditions and in the case of the structures surface, attached incoming salt may be carried away due to the rainfall. Therefore, this study aims to draw an improved proportional relation between the amount of sodium chloride in atmosphere and that attached to the surface of architectural structures by measuring the amount attached to each architectural material using artificial incoming salt generator that can control various climatic variables that can be caused in real environment.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2009년도 춘계학술대회 논문집
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• pp.123-124
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• 2009

염화물이 전기아연도금에 미치는 영향을 분석해본 결과 염화물의 양이 부족한 경우에는 도금이 원활하지 않았지만 교반속도를 충분히 주면 도금이 가능하였고, 염화칼륨의 양에 따라서 우선성장하는 면이 달랐으며 가격이 비싼 염화칼륨을 염화나트륨으로 대체 가능성이 확인되었다.

• 한국표면공학회지
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• 제25권3호
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• pp.117-125
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• 1992

In the electrolysis process of zinc plating impurity ions must be removed from zinc chloride plating solution because it's harmful to the current efficiency and the purity of zinc plating. In this study using zinc ball as a prcipitant instead of zinc dust, the fundamental data for continuous cementation process was studied. Based upon two series of experiments that consist of batch experiment with cylindrical zinc specimen and continuous experiment with zinc balls, following results have been obtained. In the continuous experiment all impurity ions have been removed within 1 hour regardless of various experimental conditions.

• Computers and Concrete
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• 제17권2호
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• pp.189-199
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• 2016

Chloride penetration is considered as a most crucial factor for the determination of the service life of concrete. A lot of experimental tools for the chloride penetration into concrete have been developed, however, the mechanism was based on only diffusion, although permeability is also main driving forces for the chloride penetration. Permeation reacts on submerged concrete impacting for short to long term durability while capillary suction occurs on only dried concrete for very early time. Furthermore, hydrostatic pressure increases in proportional to measured depth from the surface of water because of the increasing weight of water exerting downward force from above. It is thought, therefore, that the water pressure has a great influence on the chloride penetration and thereby on the service life of marine concrete. In this study, new experiment is designed to examine the effect of water pressure on chloride penetration in concrete quantitatively. As an experiment result, pressure leaded a quick chlorides penetration by a certain depth, while diffusion induced chlorides to penetrate inward slowly. Therefore, it was concluded that chloride should penetrates significantly by water pressure and the phenomena should be accelerated for concrete exposed to deep sea. The research is expected as a framework to define the service life of submerged concrete with water pressure and compute water permeability coefficient of cementitious materials.

• 한국해양공학회지
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• 제14권4호
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• pp.23-29
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• 2000

When the concrete structures were being made with sand containing chloride ion it was knows that corrosion rate of reinforced steel embedded in concrete with chloride ion was higher than that of concrete with on chloride ion. In this study, the operation of Friedel salts affecting the corrosion behavior of reinforced steel embedded in cement mortar was investigated with electrochemical view. Corrosion potential of reinforced steel embedded in cement mortar with sand containing chloride ion was shifted noble direction than that of cement mortar with no chloride ion after immersed 5 month in natural sea water and also corrosion current density decreased with shifting corrosion potential to noble direction. However Friedel salts appeared from surface to 2.5cm of inside direction of mortar specimen, which is located at 11.5$\circ$(2$\theta$) in XRD analysis and the amount of Ca(OH)2 by SEM photograph in cement mortar with chloride ion was larger than that of cement mortar with mo chloride ion. Eventually it is suggested that Friedel salts was resulted from chloride ion and it acted as the corrosion inhibitor.

• 공업화학
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• 제10권1호
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• pp.85-92
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• 1999

고정층 촉매 반응기를 이용하여 ${\gamma}$-알루미나에 담지한 크롬산화물 촉매상에서 vinyl chloride의 완전산화잔응을 $240{\sim}300^{\circ}C$의 온도와 600~3,500 ppm의 농도범위에서 조사하였다. 반응은 vinyl chloride의 농도에 대하여 비선형적으로 변하였으며, 산소의 농도에 대하여는 0차 거동을 보였다. 또한 반응 생성물인 $H_2O$와 HCl를 반응물에 첨가하였을 때 vinyl chloride의 전환율에 영향이 거의 없었다. Vinyl chloride의 산화반응에 대한 몇 가지 반응모델을 가정하고 실험결과와 상관시켜 가장 잘 일치하는 모델을 도출하였다. 속도식의 해석결과 vinyl chloride의 산화반응은 산소로 피복된 촉매표면에 vinyl chloride가 흡착한 후 산화분해되며, vinyl chloride가 촉매표면에 흡착하여 반응을 방해한다는 가정하에서 도출된 반응속도 모델이 실험결과를 가장 잘 표현하였다. 실험치와 예측치간의 표준편차 백분율은 약 5.2% 정도였으며 활성화에너지는 18.9 kcal/mol으로 계산되었다.

• 한국구조물진단유지관리공학회 논문집
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• 제26권6호
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• pp.148-156
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• 2022

대부분의 국내 콘크리트 구조물이 동결융해 및 염해 환경에 동시에 노출됨에도 불구하고 현장에서의 콘크리트 내구성능 평가는 각각의 단일 작용에 의한 손상을 평가하고 있으며 염해 손상은 현장에서 코어를 별도로 채취하여 추가적인 실내 실험분석까지 요구된다. 그러나 국내에서는 2018년부터 「시설물의 안전 및 유지관리에 관한 특별법」과 「지속가능한 기반시설 관리 기본법」 등의 시설물 유지관리를 강화하는 정책들이 수립 및 시행됨에 따라 정부 및 지자체에서 안전점검 관리 대상시설물이 증대되어 시설물이 안전 점검 및 진단에 대한 효과적인 점검 간소화 기술이 필요한 실정이다. 따라서 이 연구에서는 기존의 피복부 콘크리트 품질을 평가하는 표면반발경도를 활용하여 동해 손상이 발생한 콘크리트 부위를 대상으로 염해 손상의 가속화 정도를 판단할 수 있는 방법의 가능성을 평가하고자 하였다. 이를 위하여 동결융해 촉진 환경에 노출시켜 이미 동해 손상이 발생한 콘크리트 실험체를 염수에 침지시킨 후 콘크리트 내 침투한 염화물을 분석하여 동해 손상 정도에 따른 염화물 침투 가속화 관계를 분석하였다.

• 콘크리트학회논문집
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• 제14권5호
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• pp.708-717
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• 2002

해안 등 열악한 환경에 노출되는 구조물들의 건설이 증가되면서 구조물의 내구성 문제가 심각해지고 있다. 특히, 염해만이 아니라 염해와 황산염 그리고 중성화 등 복합작용에 의한 열화문제는 아직도 연구된 바가 거의 없는 실정이다. 따라서, 본 연구에서는 염해와 황산염 및 중성화가 복합된 환경하에서 콘크리트 구조물의 성능저하 현상을 살피고 이들의 상호작용과 영향을 실험적으로 구명하는데 그 목적을 두고 있다. 이를 위해서 단일 및 복합열화 실험을 포괄적으로 수행하였다. 본 연구결과, 염소이온 단일열화시 보다 황산염 또는 황산염과 중성화가 복합되었을 경우의 열화현상이 더 두드러졌으며, 모든 열화조건에서 표면염소이온의 농도는 시간에 따라 증가하고 반면에 확산계수는 시간에 따라 감소하는 경향을 나타냈다. 표면염소이온 농도는 복합열화에서 더 증가하며 특히 염소이온 확산계수는 염해와 황산염 2중 복합열화시 더 커지고 여기에 중성화가 복합될 경우 더욱 커지는 것으로 나타났다. 따라서, 해안 구조물과 같이 염해와 황산염 및 중성화가 복합될 경우 염소이온의 침투가 더욱 커져 이들의 합리적인 고려가 필요한 것으로 나타났다.