Electrochemical behaviour of Cu-40Zn in 3% NaCl solution polluted by sulphides: Effect of aminotriazole

The electrochemical behaviour of Cu-40Zn alloy, in 3% NaCl medium pure and polluted by 2 ppm of S²⁻ ions, has been studied in the absence and presence of the 3-amino-1,2,4 triazole (ATA) as corrosion inhibitor. Electrochemical measurements (polarisation curves and electrochemical impedance spectroscopy) showed that sulphides accelerate the alloy corrosion. The studies revealed that ATA inhibits both cathodic and anodic reactions, indicating a mixed type of inhibition. The inhibiting effect was higher in presence of S²⁻ ions than in its absence. Scanning electron microscopy analysis showed that the inhibitor acts by preventing the adsorption of S²⁻ ions, and formation of Cu₂S at the alloy surface. The inhibition efficiency reaches 98% at a concentration of 5 × 10⁻³ M.