• 대한환경공학회지
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• 제30권8호
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• pp.798-807
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• 2008

연안지역 주위에 설치된 각종 관망시설의 금속부식으로 인한 경제적 손실 때문에 실제적인 부식 거동을 이해하고 그것을 적절하게 조절하기 위한 부식과 관련된 원인-결과에 대한 정보를 필요로 하고 있다. 본 연구에서는 미생물 제어에 따라 금속 부식에 영향을 미치는지를 조사하기 위하여 실험실 규모로 연구를 수행하였다. 먼저 관망의 막힘 현상이 발생하는 곳(즉, I Gas Station)의 지하수를 채취한 후 16S rDNA방법으로 시료 속의 미생물 다양성을 조사하였다. 이로부터 금속을 부식시키는 거동이 관측된 미생물이 Leptothrix sp.(철산화)와 Desulfovibrio sp.(황환원)임을 알 수 있었다. 실험 결과, 철 시편의 경우 철산화 미생물에 의해 부식속도가 가장 크게 증가하였고, 반면 황환원 미생물에 의해 철침전물이 빠르게 형성되었다. 함석 시편과 스테인리스 스틸의 경우 주로 철산화 미생물이 부식뿐만 아니라 침전물 형성 속도를 증가시키는 데에도 매우 관련이 높았다. 아연 시편의 경우, 황환원 미생물이 철산화 미생물보다 더 부식에 대한 영향이 컸다. 또한 미생물 성장 제어실험에서는 염소주입이나 UV 처리는 효과적으로 미생물의 성장을 조절할 수 있었다. 그러나 미생물 제어 강도가 경계치보다 증가한다면 화학적 반응을 증가시키기 때문에 부식속도는 점차 증가하는 현상이 나타났다. 본 연구에서는 미생물 금속 부식은 미생물 종류나 금속재료에 따라 다르게 발생하며, 관련 미생물(Leptothrix sp.와 Desulfovibrio sp.)과 금속 부식 또는 침전물 생성에 높은 연관성을 가지고 있었다. 그리고 효과적인 미생물의 제어를 통해 부식 또는 침전 속도를 늦출 수 있음을 확인하였다.

• Corrosion Science and Technology
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• 제2권1호
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• pp.26-29
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• 2003

This study determined that the four corrosive characters of carbon steel in the marine splash zone (MSZ) in China's four sea areas. It has a range and a corrosion peak value. The rust in the MSZ plays the role of "depolarizer" in the cathodic process of corrosion. The growth law of the rust layer in MSZ has a character of "annual ring". In addition the reasons causing serious corrosion of carbon steel in the marine splash zone has been discussed in this paper.

• Corrosion Science and Technology
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• 제16권4호
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• pp.187-193
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• 2017

Polymer amines are found to show distinct corrosion inhibition effects in acidic media. The functional groups of organic compounds have a wide role in the physical and chemical properties, for the inhibition efficiency with respect to steric factors, aromaticity, and electron density. The influence of $H^+$ ions and $Cl^-$ ions on the corrosion inhibitive effect of poly(p-aminophenol) for iron in hydrochloric acid was studied using electrochemical methods such as impedance, linear polarization, and Tafel polarization techniques. The experiments were conducted with and without the inhibitor, poly(p-aminophenol). The concentration range of $H^+$ ions and $Cl^-$ ions are from 1 M to 0.05 M and 1 M to 0.1 M, respectively. With the inhibitor poly(p-aminophenol), this study shows that inhibition efficiency decreases with the reduction of $H^+$ ion and $Cl^-$ ion concentrations in aqueous solution. Further, it reveals that the adsorption of an inhibitor on the surface of iron is dependent on the concentrations of $H^+$ and $Cl^-$ ions in the solution and the adsorption of inhibitor on the iron surface through the cationic form of amine.

• Journal of Electrochemical Science and Technology
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• 제9권4호
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• pp.260-275
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• 2018

The corrosion inhibition of cast iron in 1 M HCl by Phenanthroline (Phen) was investigated using potentiodynamic polarization (PDP) curves, electrochemical impedance spectroscopy (EIS), surface analysis and theoretical calculations. It is found that Phen exhibits high inhibition activity towards the corrosive action of HCl and its adsorption obeys the Langmuir adsorption isotherm model. The results showed that inhibition efficiency increases with Phen concentration up to a maximum value of 96% at 1.4 mM, and decreases slightly with the increase in temperature. The free adsorption energy value indicates that Phen adsorbs on cast iron surface in 1 M HCl via a simultaneous physisorption and chemisorption mechanism. Scanning electron microscopy (SEM) micrographs, atomic force microscopy (AFM) and FTIR analysis confirmed the formation of a protective film on cast iron surface, resulting in the improvement of its corrosion resistance in the studied aggressive solution. Quantum chemical calculations at the DFT level were achieved to correlate electronic structure parameters of Phen molecules with their adsorption mode.

• Corrosion Science and Technology
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• 제18권3호
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• pp.86-91
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• 2019

Generally, atmospheric corrosion is the electrochemical degradation of metal that can be caused by various corrosion factors of atmospheric components and weather, as well as air pollutants. Specifically, moisture and particles of sea salt and sulfur dioxide are major factors in atmospheric corrosion. Using galvanized steel is one of the most efficient ways to protect iron from corrosion by zinc plating on the surface of the iron. Galvanized steel is widely used in automobiles, building structures, roofing, and other industrial structures due to their high corrosion resistance relative to iron. The atmospheric corrosion of galvanized steel shows complex corrosion behavior, depending on the plating, coating thickness, atmospheric environment, and air pollutants. In addition, corrosion products are produced in different types of environments. The lifespans of galvanized steels may vary depending on the use environment. Therefore, this study investigated the corrosion behavior of galvannealed steel under atmospheric corrosion in two locations in Korea, and the lifespan prediction of galvannealed steel in rural and coastal environments was conducted by means of the potentiostatic dissolution test and the chemical cyclic corrosion test.

• 대한화학회지
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• 제56권6호
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• pp.673-678
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• 2012

변전위법과 선형분극법을 이용하여 Borate 완충용액에서 철의 부식에 대한 대기의 영향을 조사하였다. 철의 부식은 용액 속에 녹아있는 산소의 양에 크게 영향을 받았다. 용액에 녹아 있는 산소의 환원반응으로 환원전류가 증가하여 부식전위가 양의 방향으로 이동하였다. 물 또는 산소의 환원 반응에 의하여 생성된 $OH^-$ 이온은 철 전극의 전기이중층에 $OH^-$ 이온의 농도를 증가시켜 철 전극에 $OH^-$ 이온의 흡착을 용이하게 하였다. 철 전극 표면에 $OH^-$ 이온의 흡착은 Langmuir isotherm 또는 Temkin logarithmic isotherm을 이용하여 설명할 수 있었다.

• 한국표면공학회지
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• 제32권3호
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• pp.393-400
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• 1999

The surface characteristics of nitrogen ion implanted iron aluminides were investigated using various electrochemical methods in $H_2$$SO_4$+KSCN and HCl solutions. Nitrogen ion implantation was performed with doses of $3.0$\times$10^{17}$ /ions/$\textrm{cm}^2$ at an energy of 150keV. Nitrogen ion implanted iron aluminides increased the corrosion potential and significantly decreased grain boundary activation, the active current density, and passive current density. Nitrogen implanted iron aluminides with Mo increased the corrosion, pitting potential, repassivation potential and │$E_{pit}$-$E_{corr}$│ value. Whereas, implanted iron aluminides containing boron reduced the pitting and repassivation potential in comparison with nitrogen implanted iron aluminides with Cr and Mo.o.

• Corrosion Science and Technology
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• 제3권6호
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• pp.227-232
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• 2004

The carboxylates as a corrosion inhibitor has been studied by many researchers because of its environmental safety and low depletion rate. However, conventional test methods of inhibitor such as weight loss measurements, linear polarization resistance and corrosion potential monitoring etc., evaluate uniform corrosion of metals. These methods are unable to evaluate crevice-related corrosions, which are encountered in most of heat exchanging facilities. In order to choose the optimum corrosion inhibitor, the appropriate test methods are required to evaluate their performances in service environment. From this point of view, polarization technique was used to evaluate the characteristics of sodium heptanoate on corrosion behavior for carbon steel. Especially a thin film crevice sensor technique were applied to simulate the crevice corrosion in this study. From these experiments, we found that oxygen as an oxidizing agent was required to obtain stable passive film on the metal. Presence of oxygen, however, accelerated crevice corrosion. Potential shift by oxygen depletion and weakened inhibitive film inside the crevice were responsible for such accelerated feature. It is shown that film for corrosion inhibition is a mixture of sodium heptanoate and iron (II) heptanoate as reaction product of iron surface and sodium heptanoate. The iron (II) heptanoate which has been synthesized by reaction of heptanoic acid and ferrous chloride in methanol solution forms bidentate complex.

• Corrosion Science and Technology
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• 제15권4호
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• pp.171-181
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• 2016

In this work, synergistic corrosion inhibition effect of nitrite and 3 kinds of ethanolamines on ductile cast iron using chemical and electrochemical methods was evaluated. This work attempts to clarify the synergistic effect of nitrite and ethanolamines. The effects of single addition of TEA, DEA, and MEA, and mixed addition of nitrite plus TEA, DEA or MEA on the corrosion inhibition of ductile cast iron in a tap water were evaluated. A huge amount of single addition of ethanolamine was needed. However, the synergistic effect by mixed addition was observed regardless of the combination of nitrite and triethanolamines, but their effects increased in a series of MEA + nitrite > DEA + nitrite > TEA + nitrite. This tendency of synergistic effect was attributed to the film properties and polar effect; TEA addition couldn't form the film showing high film resistance and semiconductive properties, but DEA or MEA could build the film having relatively high film resistance and n-type semiconductive properties. Moreover, it can be explained that this behaviour was closely related to electron attractive group within the ethanolamines, and thus corrosion inhibition power depends upon the number of the electron attractive group of MEA, DEA, and TEA.

• 보존과학회지
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• 제29권4호
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• pp.297-309
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• 2013

철제유물은 출토되는 순간 급격한 환경변화로 인해 빠른 속도로 부식이 진행되므로 보존처리 과정을 거쳐 부식을 억제한다. 그러나 보존처리가 완료된 철제유물도 재부식이 발생하는 경우가 다수이며, 재부식된 유물의 보존처리는 1차 보존처리 시보다 그 처리가 어렵고 처리기간 또한 길어진다. 본 연구는 보존처리가 완료된 이후 보관과정에서 발생하는 부식생성물을 과학적으로 분석하여 재부식의 요인을 찾고자 하였다. 경주지역의 세 유적에서 출토된 철제유물을 동일한 약품과 방법으로 2002~2009년 동안 보존처리를 완료하였으나, 포장 보관 상태의 일부 철제유물에서 재부식 징후가 관찰되었다. 이중 재부식의 징후가 확인된 단조 철제유물 9점을 선별하여 질량측정, 육안관찰, 현미경을 통한 물리적 변화를 관찰하였고, SEM-EDS, XRD, IC, ICP분석을 통해 화학적 변화를 분석하였다. 그 결과, 유물에서 탈락된 부분의 접면에 형성된 황갈색 부식생성물은 군집한 형상만 다를 뿐 결정상은 공통적으로 침상형이 확인되었으며, 적색에서 황갈색으로 갈수록 침상의 형태가 뚜렷하였다. 보존처리가 완료된 시점의 경과에 따라 부식생성물이 증가할수록 유물의 질량이 증가하였고 염화이온의 농도가 상대적으로 높아지는 경향이 나타났다. 채집된 모든 시료의 부식생성물에 대한 XRD분석에서는 ${\beta}$-FeOOH(akaganeite)이 확인되었고, ICP분석 결과 $Na^+$, $Ca^{2+}$성분을 확인할 수 있었다.