ASSESSMENT OF POLYESTER AND POLYVINYLESTER COATINGS IN A SIMULATED FGD SCRUBBING LIQUID WITH EIS

摘要

Corrosion behaviours of carbon .steel coated with polyester anil polyvinylester in a simulated flue gas desulphurisation (FGD) fluid (i.e., a mixture of H2SO4 and 0.1 wt% Fe2(SO,|)i at pH=2) have been investigated with electrochemical impedance spectroscopy (ELS). The protective nature of the coatings at 25°C has been observed in the following order: polyvinylcster primer polyvinylester topcoat > polyester topcoat > polyester primer. Coating deterioration occurred and the coating deterioration rate accelerated with increasing temperatures upto B5°C. However, the corrosion resistance sequence has remained the .same. Equivalent circuits are suggested for various coatings to discuss their mechanisms in this work.