Protection from Acid Corrosion of St3 and 10X18N10T Steels with Inhibitors Based on Tree Bark Extracts

The effect of temperature and composition of inhibitor compositions based on aqueous extracts of aspen bark (EXA), spruce (EXS), and pine (EXP) on the corrosion of St3 carbon steel in 2M sulfuric acid, used for etching steel products, and 10X18N10T(10Cr18Ni10Ti) austenitic steel in 1.4 M hydrochloric acid, used with the addition of an inhibitor for washing and chemical cleaning of cooking and heat exchange equipment, was studied for the first time using gravimetric and electrochemical methods. New data on the kinetics and mechanism of acid corrosion of the studied steels were obtained and analyzed. It has been shown that with the same content of 1 g/L inhibitory action Z water-extractive substances (WESs) of tree bark on acid corrosion of steels increases in the series EXP < EXS < EXA, as well as with an increase in the concentration of WES to 4.0 g/L and temperatures from 20 to 60°C, when mixing bark extracts of different species and even more significantly (Z = 90–97%) when hexamethylenetetramine or potassium iodide synergists are introduced into aqueous extracts¹.