Corrosion behaviour of copper in LiBr solutions – surface examination

Optical microscope (O.M) and scanning electron microscope (SEM) equipped with energy dispersive X‐ray (EDX) were used to follow the changes that occurred on the surfaces of copper after treated electrochemically in concentrated solutions of LiBr (up to 9 M). Results showed the existence of protective film of CuO and Cu(OH) 2 which are recorded during the passive film formation in 5 × 10 –1 M LiBr at 200 mV. At 1 M LiBr and during the partial passive region (600 mV) a porous film of Cu 2 O with a small ratio of CuOH and Cu(OH) 2 were detected which confirmed the higher current density recorded. On the other hand and at the same concentration (1 M LiBr at 1000 mV), surface examination confirmed the detection of CuBr 2 with small ratio of CuO which explain the deleterious effect of bromide and the autocatalytic dissolution of Cu at this higher potential. At higher concentrations from 4 to 9 M, the film formed is non homogeneous with a more porous structure which is mainly CuBr and some area of the film suffered from cracking. This proves the general dissolution through the complexing formation of soluble CuBr 2 – .