Copper corrosion inhibition in chloride environments by 3-(N-hetaryl)-5-amino-1H-1,2,4-triazoles

According to the results of experimental electrochemical measurements and corrosion tests, the effectiveness of inhibiting copper corrosion in chloride media by N-hetaryl derivatives of 5-amino-1H-1,2,4-triazole was evaluated. It was found that addition of any of the organic additives studied into a borate buffer solution in the presence of 10 mM NaCl leads to a significant ennoblement of the pitting potential of copper electrode. At the same time, the anodic and cathodic processes on copper in the presence of 3-(4-methylpiperazin-2-yl)-5-amino-1H-1,2,4-triazole at a concentration of 0.1-1.0 mM generally proceed at a higher rate than in the absence of an organic additive. On the contrary, addition of 3-(piperidin-l-yl)-, 3-(4-phenylpiperazin-2-yl)- and 3-(4-b enzylpiperazin-1-yl)-5-amino-1H-1,2,4-triazoles to the solution decreases the rate of both the cathodic process and anodic oxidation of copper, regardless of the nature of an inhibiting additive and its concentration. In addition, in the presence of these inhibitors, the current density of copper electrode passivation decreases markedly. All the compounds studied are characterized by moderate degrees of copper protection in neutral chloride media (at least 56%). The degree of protection against acid corrosion for all the inhibitors studied is 30-60% and increases with increasing concentration of an organic additive. The greatest protective effect is provided by 3-(piperidin-1-yl)-5-amino-1H-1,2,4-triazole in neutral or acidic chloride solutions. None of the inhibitors proved to be highly effective against atmospheric corrosion of copper: the first corrosion damage appears within 40-60 hours. Using DFT simulations, a correlation was found between the inhibitory effect and the molecular structure of the 5-amino-1H-1,2,4-triazole derivatives studied.