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Determination of optimum protection potential for cathodic protection of offshore wind-turbine-tower steel substructure by using potentiostatic method

정전위법에 의한 해상풍력 타워 구조물용 강재의 음극방식을 위한 최적방식전위 결정

  • Lee, Jung-Hyung (Dongnam Regional Division, Korea Institute of Industrial Technology) ;
  • Jung, Kwang-hu (Division of Marine Engineering, Mokpo National Maritime University) ;
  • Park, Jae-Cheul (Machinery Technology Research Team) ;
  • Kim, Seong-Jong (Division of Marine Engineering, Mokpo National Maritime University)
  • Received : 2016.12.19
  • Accepted : 2017.01.26
  • Published : 2017.03.31

Abstract

In this study, electrochemical methods were used to determine the optimum protection potential of S355ML steel for the cathodic protection of offshore wind-turbine-tower substructures. The results of potentiodynamic polarization experiments indicated that the anodic polarization curve did not represent a passivation behavior, while under the cathodic polarization concentration, polarization was observed due to the reduction of dissolved oxygen, followed by activation polarization by hydrogen evolution as the potential shifted towards the active direction. The concentration polarization region was found to be located between approximately -0.72 V and -1.0 V, and this potential range is considered to be the potential range for cathodic protection using the impressed current cathodic protection method. The results of the potentiostatic experiments at various potentials revealed that varying current density tended to become stable with time. Surface characterization after the potentiostatic experiment for 1200 s, by using a scanning electron microscope and a 3D analysis microscope confirmed that corrosion damage occurred as a result of anodic dissolution under an anodic polarization potential range of 0 to -0.50 V, which corresponds to anodic polarization. Under potentials corresponding to cathodic polarization, however, a relatively intact surface was observed with the formation of calcareous deposits. As a result, the potential range between -0.8 V and -1.0 V, which corresponds to the concentration polarization region, was determined to be the optimum potential region for impressed current cathodic protection of S355ML steel.

Acknowledgement

Grant : 해상 풍력 구조물의 설계수명 확보를 위한 최적 부식관리기술 개발

Supported by : 한국에너지기술평가원(KETEP)

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