Abstract
Inhibition effects and mechanism of benzotriazole (B.T.A.) on corrosion of Cu in NaCl, NaClO4, and HClO4 solutions were studied by potentiostatic polarization curves, electrical double layer (e.d.l.), and capacity-electrode potential curves; and by the relation between inhibition efficiency (P) determined by immersion test and degree of surface coverage (Q) obtained from e.d.l. capacity in Cu-NaCl-B.T.A. system. Each of the values of P and Q were measured as functions of B.T.A. concentration (m). The results obtained were as follows: (1) The inhibition effect of B.T.A. in Cu-NaCl system depended on its concentration and electrode potential. In anodic potential region, it was found that B.T.A. had little effects in low concentration, but a good inhibition effect was obtained in high concentration, because B.T.A. -Cu complex was formed and adsorbed on the surface. Whereas, in cathodic potential region, inhibition effects were found in both of low and high concentrations, owing to chemisorption of B.T.A. on the surface with a lone electron-pair of N-atom. (2) However, in Cu-NaClO4 system, it was observed that B.T.A. in low concentration had good inhibition effects in anodic and cathodic potential regions. (3) It was also found that B.T.A. had little inhibition effects in acid solutions such as of HClO4, but it had maximum effects in neutral solutions such as of NaCl and NaClO4. (4) The P-m and Q-m curves obtained in Cu-NaCl-B.T.A. system were typical Langmuir's adsorption isotherms. Proper linear correlation was observed between P and Q, but the correlation coefficient varied according to the range of B.T.A. concentration.
