Electrochemical behaviour of Cu–Ni alloy in 3%NaCl medium polluted by sulphides: effect of aminotriazole

Abstract The behaviour of 70/30 Cu–Ni alloy in 3%NaCl medium, both pure and contaminated by 1 ppm S2-ions, has been studied in the absence and in the presence of aminotriazole at a concentration of 10-4M. Potentiodynamic and electrochemical impedance measurements showed that sulphides accelerate the corrosion of the alloy in 3%NaCl. The aminotriazole inhibited both anodic and cathodic corrosion processes. The inhibiting effect was higher when the solution contained the S2-ions. Analysis by scanning electron microscopy (SEM) showed that the inhibitor acts by establishing a very thin film on the metal surface. This film behaves as a barrier to the diffusion of dissolved oxygen and to the transport of the metal ions from the melt to the solution.