• Title, Summary, Keyword: Corrosion

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Evaluation method for time-dependent corrosion depth of uncoated weathering steel using thickness of corrosion product layer

  • Kainuma, Shigenobu;Yamamoto, Yuya;Ahn, Jin-Hee;Jeong, Young-Soo
    • Structural Engineering and Mechanics
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    • v.65 no.2
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    • pp.191-201
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    • 2018
  • The corrosion environments in a steel structure are significantly different depending on the individual parts of the members. To ensure the safety of weathering steel structures, it is important to evaluate the time-dependent corrosion behavior. Thus, the progress and effect of corrosion damage on weathering steel members should be evaluated; however, the predicted corrosion depth, which is affected by the corrosion environment, has not been sufficiently considered until now. In this study, the time-dependent thicknesses of the corrosion product layer were examined to quantifiably investigate and determine the corrosion depth of the corroded surface according to the exposure periods and corrosion environments. Thus, their atmospheric exposure tests were carried out for 4 years under different corrosion environments. The relationship between the thickness of the corrosion product layers and mean corrosion depth was examined based on the corrosion environment. Thus, the micro corrosion environments on the skyward and groundward surfaces of the specimens were monitored using atmospheric corrosion monitor sensors. In addition, the evaluated mean corrosion depth was calculated based on the thickness of the corrosion product layer in an atmospheric corrosion environment, and was verified through a comparison with the measured mean corrosion depth.

Electrochemical Analysis of the Microbiologically Influenced Corrosion of Steels by Sulfate-Reducing Bacteria

  • Moon, Kyung-Man;Lee, Myung-Hoon;Kim, Ki-Joon;Kim, Seong-Jong;Shin, Sung-Kyu;Koh, Sung-Cheol
    • Corrosion Science and Technology
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    • v.3 no.5
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    • pp.187-193
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    • 2004
  • We have investigated the differences between the general corrosion and microbiologically influenced corrosion (MIC) of steels in terms of electrochemical behavior and surface phenomena. Corrosion potential of steels in the absence of SRB (sulfate-reducing bacteria) shifted to a low level and was maintained throughout the experimental period (40 days). The potential in the presence of SRB, however, shifted to a noble level after 20 days' incubation, indicating the growth of SRB biofilms on the test metal specimens and a formation of corrosion products. In addition, the color of medium inoculated with SRB changed from gray to black. The color change appeared to be caused by the formation of pyrites (FeS) as a corrosion product while no significant color change was observed in the medium without SRB inoculation. Moreover, corrosion rates of various steels tested for MIC were higher than those in the absence of SRB. This is probably because SRB were associated with the increasing corrosion rates through increasing cathodic reactions which caused reduction of sulfate to sulfide as well as formation of an oxygen concentration cell. The pitting corrosions were also observed in the SRB-inoculated medium.

Magnesium Thin Films Possessing New Corrosion Resistance by RF Magnetron Sputtering Method

  • Lee, M.H.;Yun, Y.S.;Kim, K.J.;Moon, K.M.;Bae, I.Y.
    • Corrosion Science and Technology
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    • v.3 no.4
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    • pp.148-153
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    • 2004
  • Magnesium thin flims were prepared on cold-rolled steel substrates by RF magnetron sputtering technique. The influence of argon gas pressure and substrate bias voltage on their crystal orientation and morphology of the coated films were investigated by scanning electron microscopy (SEM) and X-ray diffraction, respectively. And the effect of crystal orientation and morphology of magnesium films on corrosion behaviors was estimated by measuring anodic polarization curves in deaerated 3%NaCl solution. From the experimental results, all the sputtered magnesium films showed obviously good corrosion resistance to compare with 99.99% magnesium target of the sputter-evaporation metal. Finally it was shown that the Corrosion-resistance of magnesium films can be improved greatly by controlling the crystal orientation and morphology with effective use of the plasma sputtering technique.

Corrosion Measurements on Reinforcing Rebars in Reinforced Concrete Specimen (철근 콘크리트 시험편의 철근방식에 관한 측정법)

  • 이강균;장지원;한기훈;정영수
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.281-286
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    • 1997
  • Recent construction activities and maintenance of marine facilities have been accelerating to keep up with rapid economic growth in Korea. Marine concrete structures are exposed to salts an chloride from ocean environments. The corrosion of reinforcement steel caused by chloride-penetration into concrete may severely effect the durability of concrete structures. The objective of this research is to develop a durable concrete by investigating the corrosion resistance of various corrosion protection systems utilizing different water/cement ratio, silica fumes, corrosion inhibitors and etc. A tow-year verification test on various corrosion protection systems has been doing in the laboratory and at the seaside. Corrosion investigations on reinforcement steel are now under progress for more than 180 concrete specimen. Corrosion-related measurements include macrocell corrosion current, instant-off voltage between corroding and noncorroding reinforcement, chloride contents, the corroded surface areas on the reinforcement steel, and etc. A low level of corrosion is investigated on reinforcement steels in concrete specimen made with corrosion inhibitors or applied aqueous impregnating corrosion inhibitors into their surface, even though high chloride contents of concrete specimen.

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Consideration on the Risk of Corrosion Assessment in Reinforced Concrete Structure by Corrosion Potential Criterion (부식전위 기준에 의한 철근콘크리트 구조물의 부식진단의 위험성에 관한 고찰)

  • Jeong, Jin-A
    • Corrosion Science and Technology
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    • v.14 no.3
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    • pp.147-152
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    • 2015
  • Corrosion of steel reinforcement is a major factor in the deterioration of harbour and bridge structure. Steel corrosion in concrete must be checked for assessing the condition of a reinforced concrete structure. There are several ways how to measure the corrosion condition of reinforced concrete, but the corrosion potential measurement is a very simple, rapid, cost-effective and non-destructive technique to evaluate the severity of corrosion in reinforced concrete structure, therefore commonly used by engineers. However some particular situations may not relate to the reinforcement corrosion probability and a simple comparison of the corrosion potential data with the ASTM C876 Standard on steel reinforcement corrosion probability could be meaningless and not give reliable informations because of environment factors as oxygen concentration, chloride content, concrete resistance. Therefore this paper explains the risk of corrosion assessment in reinforced concrete structure and how many factors can affect the reliability of the corrosion potential data.

Corrosion Cost and Corrosion Map of Korea - Based on the Data from 2005 to 2010

  • Kim, Y.S.;Lim, H.K.;Kim, J.J.;Hwang, W.S.;Park, Y.S.
    • Corrosion Science and Technology
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    • v.10 no.2
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    • pp.52-59
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    • 2011
  • Corrosion of metallic materials occurs by the reaction with corrosive environment such as atmosphere, marine, soil, urban, high temperature etc. In general, reduction of thickness and cracking and degradation are resulted from corrosion. Corrosion in all industrial facilities and infrastructure causes large economic losses as well as a large number of accidents. Economic loss by corrosion has been reported to be nearly 1-6% of GNP or GDP. In order to reduce corrosion damage of industrial facilities, corrosion map as well as a systematic investigation of the loss of corrosion in each industrial sector is needed. The Corrosion Science Society of Korea in collaboration with 15 universities and institutes has started to survey on the cost of corrosion and corrosion map of Korea since 2005. This work presents the results of the survey on cost of corrosion by Uhlig, Hoar, and input-output methods, and the evaluation of atmospheric corrosion rate of carbon steel, weathering steel, galvanized steel, copper, and aluminum in Korea. The total corrosion cost was estimated in terms of the percentage of the GDP of industry sectors and the total GDP of Korea. According to the result of Input/output method, corrosion cost of Korea was calculated as 2.9% to GDP (2005). Time of wetness was shown to be categories 3 to 4 in all exposure areas. A definite seasonal difference was observed in Korea. In summer and fall, time of wetness was higher than in other seasons. Because of short exposure period (12 months), significant corrosion trends depending upon materials and exposure corrosion environments were not revealed even though increased mass loss and decreased corrosion rate by exposure time.

Correlation between Corrosion Rate and Red Water on Application of Corrosion Inhibitor in Drinking Water Distribution System (배급수 계통에서 부식억제제 적용에 따른 부식과 적수와의 상관관계)

  • Woo, Dal-Sik;Ku, Sung-Eun;Lee, Byung-Doo;Kim, Ju-Hwan;Moon, Kwang-Soon
    • Journal of Korean Society of Water and Wastewater
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    • v.19 no.1
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    • pp.68-77
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    • 2005
  • This study was performed to evaluate the application of corrosion inhibitor and to examine the correlation between corrosion rate and red water in a series of batch tests and a test using auto corrosion monitoring system at A water treatment plant in Gyeonggido. The corrosion study in the auto corrosion monitoring system indicated that Fe concentration decreased by 30~50% and corrosion rate also reduced remarkably with corrosion inhibitor at $1.8mg\;PO_4/L$. After addition of corrosion inhibitor, it was indicated the effective adsorption of the inhibitor on the surface of the pipe line forming a protective film. The corrosion rate increases with the increase in Fe concentration. With $1.8mg\;PO_4/L$ of corrosion inhibitor, the corrosion rate decreased remarkably. Fe concentration had correlation to not only red water problems but also the corrosion rate that actually dissolved into the water, primarily due to the deposition of oxidized iron or other compounds as a scale, which serves as a large reservoir of corrosion by-product. Therefore, corrosion rate can be estimated by Fe concentration. For these reasons, an effective corrosion inhibitor is also an effective red water control reagent. The effect of the corrosion inhibition can last for some time even the application the corrosion inhibitor is discontinued. For the cost effective and efficient corrosion control, the concentration and timing of corrosion inhibitor addition must be determined properly.

Characteristic of Steel Corrosion in Carbonated Concrete

  • You, JeiJun;Ohno, Yoshiteru
    • Corrosion Science and Technology
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    • v.4 no.4
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    • pp.130-135
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    • 2005
  • In this study, accelerated corrosion tests were conducted on concrete specimens with and without accelerated carbonation beforehand for the purpose of elucidating the effects of carbonation, cover depth, and water-cement ratio (W/C) on the reinforcement corrosion. During testing, the corrosion current between the anode steel and cathode stainless steel was measured to continuously monitor the progress of corrosion throughout the test period, thereby investigating the mechanism of reinforcement corrosion and the relationship between corrosion and crack width, as well as other parameters.

A Study On the Corrosion Tendency of Bottom Plates and Corrosion Prevention Measures in Hazmat Tanks (위험물저장탱코밑판의 부식 성향분석 및 부식예방 방안에 관한 연구)

  • Choi, Jeong Soo;Ro, Kyung Jin
    • Journal of the Society of Disaster Information
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    • v.4 no.1
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    • pp.138-152
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    • 2008
  • The most important factor in the maintenance of chemical industry facilities is related with deterioration and corrosion. Leakage of hazardous materials is likely to occur because the confirmation and maintenance of bottom plates are very difficult while the bottom corrosion of the massive hazmat-storage facilities is most dangerous especially. As a result of the analysis of the corrosion locations, areas, usage condition of 287 hazmat-storage tanks on this syudy, it is concluded that the main external corrosion factors are the inflow of moisture and the materials inducing corrosion in the air such as sodium chloride and the main internal corrosion factors are corrosion react caused by stay of seawater, sulfur and moisture in hazmat for a long time without appropriate discharges. It is anticipated that the corrosion of bottom plates can be restrained effectively by establishing the proper measures for the each corrosion cause.

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A Study on the Corrosion Monitoring of Multi-functional Sensors for Reinforced Concrete Structures: Part 1 (철근 콘크리트 구조물용 다기능 멀티센서의 부식 모니터링에 관한 연구: Part 1)

  • Jin, Chung-Kuk;Jeong, Jin-A;Kyoung, Eun-Jin
    • Corrosion Science and Technology
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    • v.11 no.6
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    • pp.270-274
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    • 2012
  • This study represents the result of corrosion monitoring on reinforced concrete specimens by means of multi-functional corrosion monitoring sensors. To confirm the effectiveness of the sensors, eight different kinds of condition were adopted. Test factors were corrosion potential, current, corrosion rate, resistivity, and temperature, which were monitored with the sensors. Through this study, judging corrosion of steel in concrete with single corrosion factor such as corrosion potential was difficult, because many other factors can have an influence on the reaction of corrosion. By using three different kinds of sensors, it could enhance the accuracy of corrosion monitoring.