Characterization of self-assembled layers made with stearic acid, benzotriazole, or 2-mercaptobenzimidazole on surface of copper for corrosion protection in simulated urban rain

Two procedures (one-step and two-steps) of combining stearic acid and corrosion inhibitor (1H-benzotriazole or 2-mercaptobenzimidazole) to produce self-assembled layers on surface of copper to protect it against corrosion in simulated urban rain were studied. The contact angle measurements showed that surfaces of layers made with combination of stearic acid and 2-mercaptobenzimidazole or 1H-benzotriazole and layers only made with stearic acid were hydrophobic. Energy dispersive X-ray spectroscopy and glow discharge optical emission spectroscopy analyses clearly highlighted that both stearic acid and organic inhibitors are involved in the protective film formation. Potentiodynamic curves confirm that one-step combinations (self-assembling in a mixture of stearic acid and inhibitor) exhibit better protection compared to layers made with individual inhibitors only and compared to two-steps procedure (self-assembling by successive immersion in inhibitor and stearic acid), regardless the type of inhibitor employed. Fast process of self-assembling under optimal conditions produces thin, hydrophobic protective layers on copper suitable for use under conditions of atmospheric corrosion. The tests in spray chamber show that the corrosion protection of Cu is provided after long-term exposure to simulated urban rain. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim