YANG Min-na,LU Lin,GAO Jin,LI Xiao-gang.Effects of Drinking Water Hardness on Corrosion Mechanism of Defected Coating[J],44(3):41-46,94
Effects of Drinking Water Hardness on Corrosion Mechanism of Defected Coating
Received:December 02, 2014  Revised:March 20, 2015
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DOI:10.16490/j.cnki.issn.1001-3660.2015.03.007
KeyWord:coating  corrosion  drinking water  defect  delamination
           
AuthorInstitution
YANG Min-na Corrosion and Protection Center, University of Science and Technology Beijing, Beijing , China
LU Lin Corrosion and Protection Center, University of Science and Technology Beijing, Beijing , China
GAO Jin Corrosion and Protection Center, University of Science and Technology Beijing, Beijing , China
LI Xiao-gang Corrosion and Protection Center, University of Science and Technology Beijing, Beijing , China
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Abstract:
      Objective The corrosion mechanism of defected zinc rich epoxy coating was studied in simulated drinking water with different hardness, which will be valuable for the selection of the coating used in the inner wall of drinking water pipes. Methods The electrochemical behavior of the coating during the immersion was studied by electrochemical impedance spectroscopy (EIS). The morphology and composition of corrosion products were investigated by scanning electron microscope (SEM), energy dispersive spectrometer (EDS) and Raman spectra. Results The results showed that the sample immersing in the solution containing higher concentration of Ca2+ were protected by incrustation covering the defect, which delayed the process of cathodic disbonding. In the solution containing lower concentration of Ca2+, the coating blistered around the defect because of the loose accumulation of the corrosion products. Conclusion The coating had better permeability resistance in soft water while had better cathodic disbonding resistance in hard water. Some suggestion for the application of coatings in drinking water was given at last.
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