Corrosion protection of brasses and zinc in simulated urban rain Part I: Individual inhibitors benzotriazole, 2-mercaptobenzimidazole and stearic acid

摘要

Self-assembled surface layers of benzotriazole (BTAH), 2-mercaptobenzimidazole (2-MBI) and stearic acid (SA), were studied as protective layers for brasses (Cu10Zn and Cu40Zn) and Zn in simulated urban rain (pH=5). Layers were formed by immersion of samples in ethanol solution of organic inhibitors BTAH, 2-MBI and SA. The results of weight loss immersion tests, polarization measurements and electrochemical impedance measurements showed that SA layers provided the best long term corrosion protection of all tested inhibitors and exhibited the highest contact angles. 2-MBI provided less protection than SA. BTAH can be ruled out as a corrosion inhibitor under tested conditions, because it performed poorly upon long term immersion. In the cases of Cu40Zn and Zn it even promoted corrosion.