Electrochemical behaviour of interface of carbon steel/solution containing three-component formulations

Two phosphonic acids namely 1-hydroxyethane-1,1-diphosphonic acid (HEDP) and Nitrilotris(methylenephosphonic acid) (NTMP) in combination with Zn2+ and ascorbic acid (AA) are known to be effective inhibitor systems for corrosion control of carbon steel in aqueous environments. The present study was aimed at exploring modifications occurring at the interface of carbon steel and the solutions containing HEDP-Zn2+-AA and NTMP-Zn2+-AA using electrochemical studies. The nature of the interface is found to change in presence of the formulations. The formulations affect both the anodic and cathodic partial reactions occurring on the substrate. The effects of immersion time and temperature are also studied.