Evaluation of the Protective Performance of Several Duplex Systems Exposed to Industrial Atmosphere

Abstract

The atmospheric corrosion behaviour of galvanised steel sheets and steel/55%Al-Zn system with or without different paint schemes was analysed. The samples were exposed to the atmosphere in the experimental station of CIDEPINT. Periodically, all specimens were visually inspected and sampling was made to evaluate the general behaviour of the protective system. Normalised physicochemical and EIS tests were performed on each specimen. The corrosion products were characterised by SEM. The data included in the present work concern to the first step of exposure (800 days). The foreseen whole period of testing is 7 years. From the present results may be concluded that: 1) on the analysed industrial environment, the bare sheets of steel/55%Al-Zn system have suffered less damage than the bare galvanised ones, 2) chloride and sulphide are present in the corrosion products denoting the aggressiveness of environment, and 3) in general, all duplex systems have shown a fairly good protective behaviour.