Compositions Based on the Extracts of Oak Bark and Chips as Corrosion Inhibitors for Medium-Carbon Steels in Water

We separated the extracts of oak bark and chips and prepared synergetic compositions based on these extracts and protecting medium-carbon steels against corrosion in water by 80–95%. The TIS-4 composition containing both the inorganic and organic synergists proves to be the most efficient inhibitor. The results of electrochemical investigations demonstrate that, under the influence of these inhibitors, a chemisorption film is formed on the metal surface, which increases the polarization resistance, the resistance to charge transfer, and the activation energy of corrosion. At the same time, both electrode reactions are inhibited. The developed compositions are inhibitors of mixed action and prove to be efficient in medium-hardness waters.