Electrochemistry and surface analysis of the effect of benzotriazole on the cut edge corrosion of galvanized steel

The effect of benzotriazole (BTAH) in high concentration on the cut edge corrosion of galvanized steel in sodium chloride solution was studied, using electrochemical polarization, EIS, SVET and XPS. It was observed that there is the formation of a BTAH surface film on both steel and zinc, which polarizes anodically both metals, greatly reducing their electrochemical activity and changing the rate control from diffusion at the cathode to mixed control. The protective film undergoes numerous events of local activation and repassivation. The XPS data revealed that the BTAH becomes differently bound to zinc depending on the metal being under self-corrosion or coupled to steel. Although the BTAH reduces the electrochemical activity of both materials, there is significant reduction of the cathodic protection effect of zinc.