Corrosion Science and Technology

  • 제20권4호
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  • Pages.175-182
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  • 2021
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  • 1598-6462(pISSN)
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  • 2288-6524(eISSN)
한국부식방식학회 (The Corrosion Science Society of Korea)
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A Study on the Corrosion Behavior of Magnesium Alloy Sealed with Chemical Conversion Coating and Sol-gel Coating

  • Lee, Dong Uk (Department of Industrial Chemistry, Pukyong National University) ;
  • Chaudhari, Shivshankar (Department of Industrial Chemistry, Pukyong National University) ;
  • Choi, Seung Yong (Department of Industrial Chemistry, Pukyong National University) ;
  • Moon, Myung Jun (Department of Industrial Chemistry, Pukyong National University) ;
  • Shon, Min Young (Department of Industrial Chemistry, Pukyong National University)
  • 투고 : 2020.03.27
  • 심사 : 2021.06.23
  • 발행 : 2021.08.31
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초록

Magnesium alloy is limited in the industrial field because its standard electrode potential is -2.363 V vs. NHE (Normal Hydrogen Electrode) at 25 ℃. This high electrochemical activity causes magnesium to quickly corrode with oxygen in air; chemical conversion coating prevents corrosion but causes surface defects like cracks and pores. We have examined the anti-corrosion effect of sol-gel coating sealed on the defected conversion coating layer. Sol-gel coatings produced higher voltage current and smaller pore than the chemical conversion coating layer. The conversion coating on magnesium alloy AZ31 was prepared using phosphate-permanganate solution. The sol-gel coating was designed using trimethoxymethylsilane (MTMS) and (3-Glycidyloxypropyl) trimethoxysilane (GPTMS) as precursors, and aluminum acetylacetonate as a ring-opening agent. The thermal shock resistance was tested by exposing specimens at 140 ℃ in a convection oven; the results showed changes in the magnesium alloy AZ31 surface, such as oxidization and cracking. Scanning electron microscope (FE-SEM) analysis confirmed a sealed sol-gel coating layer on magnesium alloy AZ31. Electrochemical impedance spectroscopy (EIS) measured the differences in corrosion protection properties by sol-gel and conversion coatings in 0.35 wt% NaCl solution, and the potentiodynamic polarization test and confirmed conversion coating with the sol-gel coating show significantly improved resistance by crack sealing.

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참고문헌

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