Electrochemical pitting corrosion behaviour of α-brass in LiBr containing solutions

The potentiodynamic anodic polarization curve of α-brass (70% Cu–30% Zn) in 1 M LiBr solution showed an initial active region of the alloy dissolution followed by two well defined anodic current peaks then a narrow passivation region before the pitting potential (Epit) is reached. The initial active anodic region exhibited Tafel slope with 90 mV dec−1 attributed to the formation of CuBr2− complexes. The anodic current peaks were attributed to the formation of CuBr and Cu2+ ions, respectively. The change of pH values of LiBr solution did not affect the anodic polarization curves of α-brass. Increasing the solution temperature from 30 to 90 °C changed the corrosion type from pitting to general one. The addition of 10−2 M benzotriazole (BTAH) to 1 M LiBr solution is completely inhibited the pitting corrosion at 30 °C while it did not inhibit the pitting at 90 °C. The inhibition effect was attributed to the adsorption of BTAH molecules on the alloy surface, which obeys Langmuir isotherm. The presence or absence of pitting corrosion was confirmed by using SEM.