ELECTRO AND PHYSICOCHEMICAL STUDY OF CORROSION INHIBITION OF CARBON-STEEL IN 3-PERCENT NACL BY ALKYLIMIDAZOLES

In this work the influence of alkylimidazoles on the electrochemical b ehaviour of carbon steel in stirred and aerated NaCl solution is studi ed. For all the organic compounds tested, the corrosion inhibition eff iciency increases with concentration. The inhibition effect has been n oticed to increase with the number of carbon atoms in the hydrophobic chain. The maximum corrosion inhibition efficiency was obtained with 1 1 carbon atoms. The low corrosion inhibition efficiency with long hydr ophobic chains can probably be interpreted by deformation of the hydro phobic head destabilises the adsorbed layer. Results obtained with N-u ndecylimidazole showed that it acts cathodically at low concentrations and anodically at high concentrations. The maximum corrosion inhibiti on efficiency was observed about the critical micellar concentration ( c.m.c). The establishment of a bimolecular layer film leads to a modif ication of the cathodic and anodic processes.