Evaluation of Protective Behavior of a Silane Coating on Acid Cleaned Mild Steel Substrate: The Effect of Addition of Benzimidazole and Benzothiazole to the Acid Cleaning Solution

The influence of adding benzimidazole (BIA) and benzothiazole (BTA) as corrosion inhibitors to the acidic solutions on corrosion behavior of silane coatings was investigated using electrochemical impedance spectroscopy (EIS), polarization test, Field Emission Scanning Electron Microscopy (FESEM) and electrochemical noise method. The results of EIS, polarization and electrochemical noise showed that the presence of inhibitors reduce severe corrosion attacks on metals' surface leading to obtain uniform silane coatings. Corrosion current density was reduced from 108 µA/cm2 in the absence of inhibitor to about 64 and 2 µA/cm2 in the presence of BIA and BTA, respectively. FESEM images confirmed that presence of inhibitors provides uniform corrosion products. Moreover, EDS Results well confirmed previous electrochemical results by claiming that benzothiazole surface adsorption is higher than benzimidazole.