• Title/Summary/Keyword: Corrosion Period

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Corrosion Image Monitoring of steel plate by using k-means clustering (k-means 클러스터링을 이용한 강판의 부식 이미지 모니터링)

  • Kim, Beomsoo;Kwon, Jaesung;Choi, Sungwoong;Noh, Jungpil;Lee, Kyunghwang;Yang, Jeonghyeon
    • Journal of the Korean institute of surface engineering
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    • v.54 no.5
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    • pp.278-284
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    • 2021
  • Corrosion of steel plate is common phenomenon which results in the gradual destruction caused by a wide variety of environments. Corrosion monitoring is the tracking of the degradation progress for a long period of time. Corrosion on steel plate appears as a discoloration and any irregularities on the surface. In this study, we developed a quantitative evaluation method of the rust formed on steel plate by using k-means clustering from the corroded area in a given image. The k-means clustering for automated corrosion detection was based on the GrabCut segmentation and Gaussian mixture model(GMM). Image color of the corroded surface at cut-edge area was analyzed quantitatively based on HSV(Hue, Saturation, Value) color space.

Sensitivity analysis of flexural strength of RC beams influenced by reinforcement corrosion

  • Hosseini, Seyed A.;Shabakhty, Naser;Khankahdani, Fardin Azhdary
    • Structural Engineering and Mechanics
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    • v.72 no.4
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    • pp.479-489
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    • 2019
  • The corrosion of reinforcement leads to a gradual decay of structural strength and durability. Several models for crack occurrence prediction and crack width propagation are investigated in this paper. Analytical and experimental models were used to predict the bond strength in the period of corrosion propagation. The manner of flexural strength loss is calculated by application of these models for different scenarios. As a new approach, the variation of the concrete beam neutral axis height has been evaluated, which shows a reduction in the neutral axis height for the scenarios without loss of bond. Alternatively, an increase of the neutral axis height was observed for the scenarios including bond and concrete section loss. The statistical properties of the parameters influencing the strength have been deliberated associated with obtaining the time-dependent bending strength during corrosion propagation, using Monte Carlo (MC) random sampling method. Results showed that the ultimate strain in concrete decreases significantly as a consequence of the bond strength reduction during the corrosion process, when the section reaches to its final limit. Therefore, such sections are likely to show brittle behavior.

Corrosion Protection Effectiveness and Adsorption Performance of Schiff Base-Quinazoline on Mild Steel in HCl Environment

  • Sayyid, Firas F.;Mustafa, Ali M.;Hanoon, Mahdi M.;Shaker, Lina M.;Alamiery, Ahmed A.
    • Corrosion Science and Technology
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    • v.21 no.2
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    • pp.77-88
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    • 2022
  • Schiff base quinazoline derivative viz., 3-((2-hydroxy-3-methoxybenzylidene)amino)-2-methylquinazolin-4(3H)-one (SB-Q), was synthesized in this study. Its corrosion protection impact on mild steel (MS) in 1 M hydrochloric acid solution was examined by performing weight loss measurements. The protective efficacy of SB-Q on MS in 1 M HCl was investigated based on its concentrations, immersion period, and immersion temperature. SB-Q was found to be an efficient inhibitor for the corrosion of MS. Its inhibition efficiency was improved by increasing the concentration of SB-Q to an optimal concentration of 500 ppm. Its inhibition efficacy was 96.3% at 303K. Experimental findings revealed that its inhibition efficiency was increased with increasing immersion time, but decreased with an increase in temperature. The adsorption of SB-Q molecules was followed the Langmuir adsorption isotherm model. The adsorption of the examined inhibitor molecules on the surface of mild steel was studied by density functional theory (DFT). DFT investigation confirmed weight loss findings.

Effectiveness of Calcium Nitrite in Retarding Corrosion of Steel in Concrete

  • Abosrra, L.;Youseffi, M.;Ashour, A.F.
    • International Journal of Concrete Structures and Materials
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    • v.5 no.1
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    • pp.65-73
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    • 2011
  • Corrosion of steel bars embedded in concrete admixed with 0%, 2% and 4% calcium nitrite (CN), having compressive strengths of 20 and 46 MPa was investigated. Reinforced concrete specimens were immersed in 3% NaCl solutions for 1, 7 and 15 days where 0.4A external current was applied to accelerate the chemical reactions. Corrosion rate was measured by retrieving electrochemical data via potentiodynamic polarization technique. Pull-out tests of reinforced concrete specimens were then conducted to assess the corroded steel-concrete bond characteristics. Experimental results showed that corrosion rate of steel bars and steel-concrete bond strength were dependent on concrete strength, amount of CN added and accelerated corrosion period. As concrete strength increased from 20 to 46 MPa, corrosion rate of embedded steel decreased. The addition of 2% CN to concrete of 20 MPa was not effective in retarding corrosion of steel at long time of exposure. However, the combination of higher strength concrete and 2% or 4% CN appear to be a desirable approach to reduce the effect of chloride-induced corrosion of steel reinforcement. After 1 day of corrosion acceleration, specimens without CN showed higher bond strength in both concrete mixes than those with CN. After 7 and 15 days of exposure, the higher concentration of CN, the higher bond strength in both concrete mixes achieved, except for the concrete specimen of 20 MPa compressive strength with 2% CN that recorded the highest deterioration in bond strength at 15 days of exposure.

Biocides Effect on the Microbiologically Influenced Corrosion of Pure Copper by Desulfovibrio sp.

  • Onan, Mert;Ilhan-Sungur, Esra;Gungor, Nihal Dogruoz;Cansever, Nurhan
    • Journal of Electrochemical Science and Technology
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    • v.9 no.1
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    • pp.44-50
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    • 2018
  • The aims of this study were to determine the corrosion behavior of pure copper in the presence of Desulfovibrio sp. and also to investigate the effects of glutaraldehyde (GD) and isothiazolinone (ISO) on the corrosion behavior of pure copper in the presence of this sulfate-reducing bacteria (SRB) strain by using electrochemical techniques. Electrochemical measurements of pure copper were carried out at specified time intervals (0, 8, 24, 48, and 96 hr) over a period of exposure. Corrosion rates of pure copper from anodic and cathodic Tafel slopes and corrosion potential ($E_{corr}$) were determined. Biofilm and corrosion products on the copper surfaces were observed by Field Emission Scanning Electron Microscopy (FESEM) and Energy Dispersive X-Ray Spectrometry (EDS) analyses. The effects of solution types (PC (Postgate's C medium) and SRB (Desulfovibrio sp.)) and exposure times of copper and biocides (ISO or GD) on the corrosion rates of pure copper were evaluated by statistical analyses. As a result of the FESEM analysis, biofilm formation was observed on the surfaces of pure copper exposed to the Desulfovibrio sp. cultures both with and without the biocides. The results show that the pure copper was corroded by Desulfovibrio sp. However, the addition of GD or ISO to the Desulfovibrio sp. culture resulted in a decrease in the corrosion rate of the pure copper. It was also observed that both of the biocides showed a similar effect on pure copper's corrosion rate caused by Desulfovibrio sp.

A Fundamental Study on the Steel Corrosion Due to Carbonation of Concrete (콘크리트의 중성화로 인한 철근의 부식에 관한 기초적 연구)

  • 이창수;윤인석;최성기
    • Proceedings of the Korea Concrete Institute Conference
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    • 1998.10c
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    • pp.203-206
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    • 1998
  • In reinforced concrete carbonation of concrete leads to depassivation of the reinforcement, and hence to initiation of corrosion. As a result of carbonation accelerating experiment with using effect of wet-dry cycle and 15% concentration of CO ₂, the carbonation rate shows very distinct difference according to W/C ratio. OPC-40 estimated no carbonation depth, whereas OPC-60 estimated rapidly the carbonation rate. The comparative analysis of the carbonation rate accelerating depends on different kinds of cement shows fastest FAC-20. Also, highly W/C ratio's concrete shows low half-cell potential value and fast corrosion rate. During period for 14 weeks. corrosion rate was not severe. So, it can be concluded that only carbonation attack on concrete doesn't severly deteriorated except very poor qualitified concrete.

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Study on the erosion-corrosion damages of pump impeller (워터펌트 내에 있는 임펠러의 침식.부식에 관한 연구)

  • Kim, Jae-Wook;Lim, Hee-Chang;Lim, Uh-Joh
    • Proceedings of the KSME Conference
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    • 2007.05a
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    • pp.102-107
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    • 2007
  • The steel impeller placed in a water pump has been studied with the aim to understand corrosion phenomena on the surface responsible for reducing the pumping efficiency of water inside cooling system. This preliminary experiment includes a period (around 1 month) observation with a powered microscope and weight measurements. The experiments are carried out at different conditions of water and mixtures of water and coolants, based on the water contents of 25%, 50%, 75%, and 100% water (pure tap water). From the visual results of microscopy, most of the steel surface is fitted and clear rusty or corrosion phenomena are noticeable as time goes. In addition, the weight loss of the sample specimen submerged in the water is linearly increased, whereas those in the mixtures of water initially gain weight and become almost constant.

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Material characteristic of ACSR due to eccentricity at sleeve point (ACSR 슬리브 개소에서의 송전선 재료특성 검토)

  • Kang, J.W.;Hong, D.S.;Jang, T.I.;Yoon, H.H.;Lee, D.I.;Choi, H.Y.
    • Proceedings of the KIEE Conference
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    • 2006.07a
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    • pp.309-310
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    • 2006
  • The considerations for remaining life of ACSR (Aluminum Stranded Conductors Steel Reinforced) in transmission lines has become gradually important to hold reliability and stability of power supply. The remaining life of ACSR exposed to the atmosphere for a long period may rely on deterioration caused by environmental indices such as atmospheric corrosion, galvanic corrosion, crevice corrosion and fatigue corrosion. This paper deals with material characteristic of ACSR due to eccentricity at sleeve point. Test samples are ACSR 240[$mm^2$] conductors, which are real transmission lines. As a result, it is obvious that ACSR due to eccentricity may lead to mechanical deterioration.

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Tensile Characteristics of ACSR Overhead Lines located in seaside (해안지역 ACSR 가공지선의 기계적 특성)

  • Jang, T.I.;Kang, J.W.;Lee, D.I.;Jang, I.C.
    • Proceedings of the KIEE Conference
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    • 2001.07c
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    • pp.1709-1711
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    • 2001
  • The remaining life of ACSR(Aluminum Conductor Steel Reinforced) wires exposed to the atmosphere for a long period relies on the extent of deterioration caused by environmental factors such as atmospheric corrosion, galvanic corrosion, crevice corrosion and fatigue corrosion. We investigated the tensile characteristics of ACSR wires in a coastal area through several mechanical tests, and analyzed the constituents of them using SEM(scanning electron microscope). Test samples are parts of ACSR 97[$mm^2$] overhead transmission lines in that area. The result shows that ACSR wires exposed to salt may lead to rapid mechanical deterioration.

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Mechanical characteristic of overhead transmission lines by forest fires (화염에 노출된 가공송전선의 기계적.재료적 특성 검토)

  • Kang, J.W.;Jang, T.I.;Kim, B.K.;Park, C.G.;Bang, H.K.
    • Proceedings of the KIEE Conference
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    • 2002.07a
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    • pp.339-341
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    • 2002
  • The remaining life of ACSR exposed to the atmosphere for a long period may rely on deterioration caused by environmental indices such as atmospheric corrosion, galvanic corrosion, crevice corrosion and fatigue corrosion. One of reduction of useful life in overhead transmission lines built on the ridge of mountain is often caused by forest fires. This paper deals with investigation of strength deterioration performance of ACSR due to fires through several testing and analyzing data for both tension load and material analysis. Test samples are ACSR $480[mm^2]$ conductors, which are artificially fired to regular durations. As a result, it can be verified that tension load of ACSR are reduced by increasing fro duration. Hence, it is obvious that ACSR due to forest fires may lead to mechanical deterioration.

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