Electrochemical behaviour of Cu24Zn5Al alloy in alkaline medium in the presence of chloride ions and benzotriazole

This paper deals with electrochemical behaviour of Cu24Zn5Al alloy in a sodium tetraborate solution (borax), in the presence of chloride ions and benzotriazole. It was found that during anodic polarization of the investigated alloy, in a sodium tetraborate solution, at lower potentials, copper (I)-oxide formed on the alloy surface. The voltammograms show peak potential shifts corresponding to the formation of Cu₂O towards more positive values with longer immersion time. It was found that chloride ions had an activating effect in a sodium tetraborate solution containing various concentrations of chloride ions (0.001, 0.005, 0.010, 0.050 and 0.100 mol dm⁻³ Cl⁻). It was observed that Cu24Zn5Al alloy corroded more intensely in more concentrated solutions and with longer exposure to Cl⁻. Investigations of the effect of inhibitor concentrations (8.4 × 10⁻⁶, 8.4 × 10⁻⁵, 8.4 × 10⁻⁴ and 8.4 × 10⁻³ mol dm⁻³ BTA in 0.1 mol dm⁻³ borax solution) showed that BTA had a good protective effect. The inhibiting effect of BTA was also confirmed with various times of immersion of this alloy in a 1.7 × 10⁻² mol dm⁻³ solution of this inhibitor.