• Title/Summary/Keyword: cathodic potential

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Study on the Characteristics of Crevice Corrosion Prevention of SS 400 in Marine Environment (해양환경 중에서 SS400강재의 간극부식방지 특성에 관한 연구)

  • 임우조;정기철;구영필;윤병두
    • Proceedings of the Korean Society of Marine Engineers Conference
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    • 2001.05a
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    • pp.152-157
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    • 2001
  • This paper was studied on the characteristics of crevice corrosion prevention of SS 400 in marine environment. In NaCl solution, polarization behavior under the crevice corrosion was investigated. And Weight loss rate of SS 400 applied cathodic protection and non cathodic protection was measured according to the NaCl concentration. The main results obtained are as follows : The weight loss rate of Al-alloy galvanic anode was increased as the concentration of NaCl solution increased by 3.5% but the concentration increased over 3.5%, that of Al-alloy galvanic anode become decreased. The protective potential of SS 400 used Al-alloy galvanic anode becomes more cathodic polarization with increasing concentration of NaCl solution. Effects of oxygen on the weight loss rate of Al-alloy sacrificial anode for cathodic protection as the concentration of 3.5% NaCl solution become sensitive than that of 0% NaCl solution.

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Synthesis of Azobenzene Derivatives via Controlled Potential Cathodic Electrolysis (조절전위법 음전극 유기반응을 이용한 아조벤젠 유도체들의 합성)

  • Kim Byeong Hyo;Choi Yong Rack;Kim Dae Ho;Han Rongbi;Baik Woonphil;Jun Young Moo
    • Journal of the Korean Electrochemical Society
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    • v.2 no.4
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    • pp.209-212
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    • 1999
  • Using an H-type divided cell, reductive coupling reaction of nitroarene toward azobenzenes in a mild condition was successfully accomplished by the controlled potential cathodic electrolysis reaction. Optimum reaction potential of each reaction was determined based on cyclic voltammetric behavior in methanol solution at Pb or Pt cathode, and Pt anode. In most cases, reductive coupling reactions were successful with excellent yields regardless of the position and the character of the substituents.

A New Protection Strategy of Impressed Current Cathodic Protection for Ship

  • Oh, Jin-Seok;Kim, Jong-Do
    • Journal of Mechanical Science and Technology
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    • v.18 no.4
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    • pp.592-596
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    • 2004
  • Corrosion is never avoided in the use of materials with various environments. The underwater hull is normally protected against rusting by several coatings of anti-corrosive paint. The purpose of ICCP(Impressed Current Cathodic protection) system is to eliminate the rusting or corrosion, which occurs on metal immersed in seawater. The anode of ICCP system is controlled by an external DC source with converter. The function of anode is to conduct the protective current into seawater. The proposed algorithm includes the harmonic suppression control strategy and the optimum protection strategy and has tried to test the requirement current density for protection, the influence of voltage, the protection potential. This paper was studied the variation of potential and current density with environment factors, time and velocity, and the experimental results will be explained.

Protection Performance Simulation of Coal Tar-Coated Pipes Buried in a Domestic Nuclear Power Plant Using Cathodic Protection and FEM Method (국내원전에 매설된 콜타르 코팅 배관의 음극방식과 FEM법을 이용한 방식성능 시뮬레이션)

  • Chang, H.Y.;Kim, K.T.;Lim, B.T.;Kim, K.S.;Kim, J.W.;Park, H.B.;Kim, Y.S.
    • Corrosion Science and Technology
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    • v.16 no.3
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    • pp.115-127
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    • 2017
  • Coal tar-coated pipes buried in a domestic nuclear power plant have operated under the cathodic protection. This work conducted the simulation of the coating performance of these pipes using a FEM method. The pipes, being ductile cast iron have been suffered under considerably high cathodic protection condition beyond the appropriate condition. However, cathodic potential measured at the site revealed non-protected status. Converting from 3D CAD data of the power plant to appropriate type for a FEM simulation was conducted and cathodic potential under the applied voltage and current was calculated using primary and secondary current distribution and physical conditions. FEM simulation for coal tar-coated pipe without defects revealed over-protection condition if the pipes were well-coated. However, the simulation for coal tar-coated pipes with many defects predict that the coated pipes may be severely degraded. Therefore, for high risk pipes, direct examination and repair or renewal of pipes are strongly recommended.

Redox Reaction on Polarization Curve Variations of Polymer with Enzymes

  • Park, Chil-Nam
    • Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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    • v.4 no.3
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    • pp.165-171
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    • 2000
  • Experiments were carried out to measure variations in the oxidation potential and current density using the polarization curves of polycarbonate. The results were then examined to identify the influences affecting the oxidation potential related to various conditions, such as temperature, pH, and oxydase(citrate and lipase). The lines representing the active anodic and cathodic dissolution shifted only slightly in the potential direction relative to temperature, pH, and the effect of the enzyme. The Tafel slope for the anodic and cathodic dissolution was determined such that the reversibility polarization was indicated as being effected by various conditions. The slope of the polarization curves describing the active-to-passive transition region shifted noticeably in their direction. Also, by varying the conditions, the optimum conditions for the most ready transform were identified, including temperature, pH, oxidation rate, and resistance of oxidation potential. The critical oxidation sensitivity(I(sub)r/I(sub)f) of the anodic current density peak and maximum passive current density was also determined, which is used in measuring the critical corrosion sensitivity of a polycarbonate.

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Effect of Zinc Addition in Filler Metal on Sacrificial Anode Cathodic Protection of Fin-Tube Aluminum Heat Exchanger

  • Yoon-Sik So;Eun-Ha Park;Jung-Gu Kim
    • Journal of Electrochemical Science and Technology
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    • v.14 no.4
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    • pp.349-360
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    • 2023
  • This study investigated the tri-metallic galvanic coupling of different metals in the tubes, fillers, and fins of a heat exchanger. The goal was to prevent corrosion of the tubes using the fin as a sacrificial anode while ensuring that the filler metal has a more noble potential than the fin, to avoid detachment. The metals were arranged in descending order of corrosion potential, with the noblest potential assigned to the tube, followed by the filler metal and the fin. To address a reduction in protection current of the fin, the filler metal was modified by adding Zn to decrease its corrosion potential. However, increasing the Zn content of filler metal also increases its corrosion current. The study examined three different filler metals, considering their corrosion potential, and kinetics. The results suggest that a filler metal with 1.5 wt.% Zn addition is optimal for providing cathodic protection to the tube while reducing the reaction rate of the sacrificial anode.

Electrochemical Characteristics of Zn-mesh Cathodic Protection Systems in Concrete in Natural Seawater at Elevated Temperature

  • Kim, Ki-Joon;Jung, Jin-A;Lee, Woo-Cheol;Jang, Tae-Seub
    • Corrosion Science and Technology
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    • v.6 no.6
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    • pp.269-274
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    • 2007
  • The corrosion of steel in concrete is significant in marine environment. Salt damage is one of the most detrimental causes to concrete bridges and port structures. Especially, the splash and tidal zones around water line are comparatively important in terms of safety and life-time point of view. During the last several decades, cathodic protection (cp) has been commonly accepted as an effective technique for corrosion control in concrete structures. Zn-mesh sacrificial anode has been recently developed and started to apply to the bridge column cp in marine condition. The detailed parameters regarding Zn-mesh cp technique, however, have not well understood so far. This study is to investigate how much Zn-mesh cp influences along the concrete column at elevated temperature. About 100 cm column specimens with eight of 10 cm segment rebars have been used to measure the variation of cp potential with the distance from Zn-mesh anode at both $10^{\circ}C$ and $40^{\circ}C$ in natural seawater. The cp potential change and current diminishment along the column specimens have been discussed for the optimum design of cp by Zn-mesh sacrificial anode.

Investigation of Optimum Cathodic Protection Potential to Prevent Erosion with a Flow Rate of AA5083-H321 for Marine Vessels (선박용 AA5083-H321의 유속에 의한 침식손상 방지를 위한 최적 음극방식전위 규명)

  • Chong, Sang-Ok;Park, Il-Cho;Kim, Seong-Jong
    • Corrosion Science and Technology
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    • v.19 no.6
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    • pp.288-295
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    • 2020
  • This study investigated the erosion-corrosion characteristics of 5038-H321 aluminum alloy in a natural seawater solution through various electrochemical experiments and flow rate parameters. Cathodic polarization experiments were conducted at flow rates ranging from 4 to 12 knots. Considering the concentration polarization section representing a relatively low current density, the range of the potentiostatic experiment was determined to be -1.6 to -1.0 V. The potentiostatic experiment was conducted at various potentials for 180 minutes in seawater. After the experiment, the corrosion characteristics were evaluated by observing surface morphology and measuring surface roughness. As a result, as the applied potential was lower, the amount of calcareous deposits increased and the roughness tended to increase. On the other hand, it was confirmed that the roughness was larger in the static condition than the flow rate condition due to the influence of the flow velocity. Variations in the chemical composition with flow rate variations were analyzed by energy-dispersive spectroscopy (EDS). In conclusion, the cathodic potential of AA5083-H321 in seawater was determined to be -1.0 V.

Effect of the Chathodic Protection in Concrete by Applying Sacrificial Anode System (희생양극방식을 응용한 콘크리트 중의 철근의 전기방식 효과)

  • 김성수;김홍삼;김진철;김종필;박광필
    • Proceedings of the Korea Concrete Institute Conference
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    • 2001.05a
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    • pp.87-92
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    • 2001
  • Reinforced concrete have defect in durability due to carbonation, freezing and thawing, and penetration of chloride ions with time in spite of superb structure. Especially steel corrosion in concrete due to penetration of chloride ions have result in a marked decline in service life. The principal purpose in this study is to see effect of sacrificial anode cathodic system, one of the electrochemical methods in order to the control of steel corrosion in concrete. There are chloride content in concrete in cracked and no cracked specimen with cathodic protection. To recognize the effect of sacrificial anode cathodic protection, Instant-off potential are measured. We have the excellent effect for control steel corrosion adaption sacrificial anode cathodic system.

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Effects of the Protection for Rebars by Embeded Sacrificial Anode in Concrete (희생양극재의 매입에 의한 콘크리트 중의 전기방식 효과)

  • 김성수;김홍삼;김종필
    • Proceedings of the Korea Concrete Institute Conference
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    • 2001.11a
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    • pp.1207-1212
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    • 2001
  • Reinforced concrete has defects in durability due to carbonation, freezing and thawing, and penetration of chloride ions with elapse of time in spite of super structure. Especially steel corrosion in concrete due to penetration of chloride ions has result in a severe decline in service life. The principal purpose of this study is to estimate effects of sacrificial anode cathodic system, one of the electrochemical methods in order to control of steel corrosion in concrete. There are chloride content in concrete in cracked and non cracked specimen with cathodic protection. To investigate the effect of sacrificial anode cathodic protection, potential-decay with current density, corrosion ratio, etc. are measured. We have the excellent effect for control steel corrosion adaption sacrificial anode cathodic system.

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