Assessment of Hybrid Amino Acid Iron Carbonate Corrosion Layer Protective Properties in a CO₂-Containing Aqueous Environment

Iron carbonate (FeCO₃) is a carbon dioxide (CO₂) corrosion by-product known to provide corrosion resistance to carbon steel in specific environmental conditions. Nonetheless, it suffers from both chemical dissolution and mechanical damage when the pH is low and when subjected to particle impingement, respectively. This work aims at understanding whether incorporating two amino acids, mainly cysteine and glycine help improve either the reduction in corrosion rate or the mechanical properties of FeCO₃. In addition to their corrosion inhibition properties, it is anticipated that incorporating such organic moieties directly into the FeCO₃ layer as it grows should have a positive effect on properties such as the modulus, in turn making the layer less prone to internal stresses and disbandment. Our results show that both amino acids incorporate within the FeCO₃ matrix and affect the hardness and modulus of the hybrid layer. Moreover, cysteine is able to reduce localized corrosion attack in such environments.