Effects of benzotriazole on the corrosion of Cu10Ni alloy in sulfide-polluted salt water

Benzotriazole (BTAH) is shown to inhibit the corrosion of the Cu10Ni alloy in salt water polluted by sulfide ions. The presence of sulfide ions (at 2 ppm) decreases the inhibiting efficiency of BTAH against the corrosion of Cu10Ni alloy. This is illustrated by measurements of the integral weight loss of the alloy, its average corrosion rate and the weight of the corrosion product film over exposure times of up to 840 h. The results are interpreted in terms of competitive adsorption of the protective BTAH and the corrosion promoting sulfide ions on the alloy surface. In the presence of high concentration of BTAH, X-ray diffraction measurements revealed the absence of copper sulfide in the corrosion product film while metallographic examination revealed a much lower extent of corrosion.