Effect of the octadecylamine:benzotriazole ratio on the protective properties of their mixture in the chamber treatment of steel

The effect of the octadecylamine:benzotriazole ratio on the protective effect of their mixture as a chamber inhibitor of steel corrosion has been studied by corrosion and electrochemical methods. It has been found that the anticorrosive aftereffect of the mixture depends on the ratio of the components. The inhibitor containing 75% of octadecylamine has the best protective properties. The mixture of octadecylamine and benzotriazole in the chamber treatment of steel is characterized by an antagonism of the protective action, but the inhibitor with the optimum composition is noticeably superior in efficiency to each component alone. The antagonism of the protective effect of octadecylamine and benzotriazole may be due to the acid-base interactions of these compounds accompanied by a decrease in the inhibitor vapor pressure. The protective action of the octadecylamine:benzotriazole mixture is caused by a stabilization of the passive state of steel that manifests itself as an increase in the pitting potential and/or anti-pitting base in chloride-containing electrolytes. The mixture studied acts by the "blocking-activation" mechanism with predominance of blocking effects.