Corrosion of α-Brass in Solutions Containing Chloride Ions and 3-Mercaptoalkyl-5-amino-1H-1,2,4-triazoles

Abstract

The protective effect of 3-mercaptoalkyl derivatives of 5-amino-1H-1,2,4-triazole against corrosion of α-brass in a chloride media was studied using polarization curves, electrochemical impedance spectroscopy, and full-scale corrosion testing. The brass electrode remains passive up to the activation potential, which is much higher than in solutions without organic additives, and it increases with the concentration of the inhibitor. The protection degree of all the studied inhibitors reaches its maximum of over 99% in solutions with the concentration of the inhibitor Cinh ≥ 0.10 mM. The protective effect increases with the length of the alkyl chain. All the studied derivatives are effective against atmospheric corrosion of α-brass. A protective film is formed on the brass surface, and it most probably includes oxides as well as complex compounds of zinc and copper with the molecules of the inhibitors. The impedance spectroscopy demonstrated that the presence of the inhibitor results in a decrease in the double-layer capacitance and an increase in the polarization resistance, which proves that the protective film actually forms on the brass surface. The quantum chemical analysis of the optimized molecular structures demonstrates that all the studied inhibitors should have a similar protective effect, which agrees with the experimental results.

Special Issue on “Advances in Organic Corrosion Inhibitors and Protective Coatings”

“…Two articles based on copper alloy corrosion protection were published in this Special Issue. In the work of Kozaderov et al [5], the corrosion inhibition efficiency of 3-mercaptoalkyl derivatives of 5-amino-1H-1,2,4-triazole for the a-brass (copper > 65 wt.% and zinc < 35 wt.%) in a chloride media was investigated using electrochemical techniques. Taking into account the obtained result, it was estimated that the degree of protection achieved for all inhibitors can reach a maximum of over 99%.…”

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Theoretical, Monte Carlo Simulations and QSAR Studies on Some Triazole Derivatives as Corrosion Inhibitors for Mild Steel in 1 M HCl

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