Evaluation of the Corrosion Behavior of the Polyester-Coated Galvanized Steel Subjected to SO_2 Gas under Different Relative Humidities

摘要

Evaluation of the corrosion behaviour of the polyester-coated galvanized steels exposed to different relative humidities was utilized using electrochemical impedance spectroscopy (EIS), anodic polarization curves and linear polarization resistance (LPR) measurement techniques. The samples were exposed to SO_2 gas in laboratory conditions that was adjusted to various relative humidities. The results obtained from current-potential curves indicate that, corrosion current density of polyester-coated samples increases as the relative humidity increases in SO_2 containing medium. The EIS results showed that polyester-coated samples exposed to relative humidity (RH) of 70% experienced defect-free coating, whereas the samples significantly lost their protection behaviour under relative humidities of 80, 90 and 100%.