The inhibition of zinc corrosion by bisaminotriazole and other triazole derivatives

The inhibition of zinc corrosion by various triazole derivatives was investigated with respect to dependence on pH, potential E, inhibitor concentration cInh, zinc ion concentration cZn2+, and exposure time t. Current potential curves and measurements of weight loss show that 3-amino-5-heptyl-1,2,4-triazole (AHT) is an excellent inhibitor of zinc corrosion in acid and weak alkaline solutions, while bisaminotriazole (BAT4) gives the best inhibition efficiency expecially at pH 9 and low inhibitor concentrations. Capacity potential curves and XPS-measurements show the formation of protective triazole layers with a maximum thickness of about 3 nm. The chemical analysis of insoluble zinc triazole complexes precipitated in solution yields a stoichiometric ratio of Zn2+ and the triazole ring of 1 : 2. The presence of zinc triazole complex on the zinc surface is shown by XPS spectroscopy. The solubility, adsorbability and hydrophobicity of the triazole molecules and the stability of the zinc-triazole complexes are found to be the most important factors influencing the inhibition efficiency of the triazole derivatives under varying conditions.