SYNERGISTIC INHIBITION EFFECT OF BENZOTRIAZOLE (BTA) AND OXALATE IONS ON THE CORROSION OF COPPER, ZINC AND BRASS IN NaCl AND HCl SOLUTIONS

摘要

Inhibition of corrosion is of high technological importance and progress made in this field has been phenomenal in recent years. Zinc is more active compared to copper. Copper is a valuable material, especially in electronics, solar cell fittings, household products, structural engineering, art and decoration, coinage and biomedical application. Even though copper is corrosion resistant due to its natural oxide film, it is prone to corrode in solutions that contain oxygen and high concentration of chloride, sulphate, sulphide and nitrate ions. A variety of potentially damaging environments require versatile inhibition actions. Although an inhibitor is sometimes added to avoid tarnishing, in the majority of cases the inhibitor's purpose is to prevent or postpone corrosion attack.The corrosion inhibition of copper, zinc and brass in 0.5 M NaCl and 0.5 M HC1 solutions in the presence of BTA and sodium oxalate have been investigated using polarization, AC-impedance and current-potential methods. Inhibition effect depends to the pretreatment of electrode. For this reason, the electrodes were pretreated in 0.15 M HC1 solution for 20 seconds in order to obtain better surface prone to form coatings on the electrode surface before immersing into the studied solutions. Results showed BTA and oxalate to have synergistic inhibition effect on the corrosion of copper and brass. All the methods employed showed good correlation between each other revealing a mean efficiency of 99% in neutral medium and 88% in acidic medium for brass.