This work reports a study of the inhibiting action of benzotriazole (BTAH) and benzimidazole (BZM) on the corrosion of 304 austenitic stainless steel (SS) in 4.5 mol/L H2SO4. All solutions were prepared with analytical degree reagents and highly purified water. The concentrations used were: [BTAH]= 1x10-5 mol.L-1 and [BZM]= 1x10-3 mol/L. The experiments were carried out at a room temperature of 26 ± 2°C. Open circuit potential (OCP), anodic potentiostatic polarisation curves (AP), electrochemical impedance spectroscopy (EIS) and optical microscopy (OM) were used in the experiments. The results of OM for BTAH + BZM showed a corrosion-inhibiting synergic effect for 304 SS. The OCP measures in the presence of BTAH, BZM or BTAH+BZM indicate an increase in corrosion potential (Ecorr), suggesting that BTAH, BZM and BTAH+BZM acted as anodic corrosion inhibitors. AP curves in the presence BTAH and BZM, individually, suggested catalytic corrosion action for 304 SS, but in the presence of BTAH+BZM, inhibitor corrosion was observed. The results of the experiments were confirmed by EIS diagrams obtained in Ecorr.
Benzotriazole; benzimidazole; corrosion; steel 304
