Corrosion Monitoring of Galvanized Steel in Simulated Wet-Dry Cyclic Condition in 0.05 M NaCl Solution

Abstract

Abstract:The corrosion monitoring of galvanized steel in 1 h wet and 7 h dry cyclic condition in 0.05 M NaCl has been carried out using AC impedance technique. During the wet-dry cycles, the polarization resistance, R p , and solution resistance, R s , were continuously monitored. The instantaneous corrosion rate of the coating was estimated from the obtained R p -1 and time of wetness (TOW) was determined from the R s values. The corrosion potential, E corr , was measured twice a day during the immersion period of wet-dry cycle. The corrosion was accelerated by the wet-dry cycles in the early stage followed by a decrease in the final stage of wet-dry cycle. The corrosion potential shifted to more negative direction for the first 8 cycles due to dissolution of air formed oxide. A gradual shift in the corrosion potential with the progress of corrosion in the later stage of the wet-dry cycle was observed due to deposition of corrosion products. The corrosion mechanism of galvanized steel is discussed based on the results of corrosion monitoring and corrosion potential variation.

Effect of Equisetum arvense extract as corrosion inhibitor of A36 steel in sulfuric acid solution

“…A positive shift of the E corr due to the presence of Equisetum arvense extract indicated that this organic compound is an effective suppressor of the anodic dissolution reaction, which could be related to the formation of a protective layer . On the other hand, the negative shift of E corr indicated the acceleration of anodic dissolution of the oxide layer . The parameters of E corr and I corr were determined by extrapolation of the cathodic polarization curve and anodic polarization curve, and IE cpt was calculated from the following equation: where I 0 corr and I corr are corrosion current densities in absence and presence of Equisetum arvense extract, respectively.…”

“…[20] On the other hand, the negative shift of E corr indicated the acceleration of anodic dissolution of the oxide layer. [21] The parameters of E corr and I corr were determined by extrapolation of the cathodic polarization curve and anodic polarization curve, and IE cpt was calculated from the following equation [22] :…”