Inhibition of dezincification of 70-30 brass by aminoalkyl mercaptotriazoles

Corrosion inhibition efficiencies of triazole derivatives for 70-30 brass in water containing 3% NaCl have been evaluated by means of weight loss, electrochemical polarisation, and impedance techniques. The triazole derivatives, namely aminomethyl mercaptotriazole (AMMT), aminoethyl mercaptotriazole (AEMT), and aminopropyl mercaptotriazole (APMT), gave inhibition efficiencies in the order APMT (94.5%) > AEMT (93.6%) > AMMT (91.5%). Nyquist plots showed Warburg impedance, i.e. the reaction was under diffusion control. The inhibition efficiencies of the triazoles did not drop under dynamic flow conditions. Solution analysis showed selective dissolution of zinc compared with copper. The lowest concentration of zinc, achieved in the tests with the optimum inhibitor addition, was 0.35 mg L-1.