Intergranular corrosion of copper in the presence of benzotriazole

While benzotriazole (BTAH, C6H5N3) has long been known as an efficient inhibitor for the general corrosion of copper, this paper documents the occurrence of intergranular corrosion (IGC) of copper in a salt solution (3.5 wt.% NaCl) in the presence of 1 mM BTAH. This occurs above a breakdown potential, Eb, at the end of the passive region. Higher concentrations of BTAH broaden the passive region and shift Eb to more noble values. Pitting is the mode of corrosion above Eb in the presence of a higher concentration of BTAH, while IGC occurs above Eb in the presence of 1 mM of BTAH.