Surface protection of low carbon steel with N-acyl sarcosine derivatives as green corrosion inhibitors

Abstract Green corrosion inhibitors are considered to have a high efficiency in steel protection without any environmental limitations. In the present work, three N -acyl derivatives of sarcosine are tested as inhibitors to reduce corrosion on low carbon steel via direct surface adsorption. Two variations of this steel type were used as basic materials to quantify the efficiency of selected sarcosine derivatives. Both variations comply with the standard, but showed different long-term corrosion behavior. Corrosion process was performed by potentiodynamic polarization and electrochemical impedance spectroscopy. A highly improved corrosion resistance for both steel variations with a direct correlation to the molecular weight and carbon chain length of the inhibitor was detected. One steel variation showed an efficiency of 88.7 % and the second up to 79.3 % for the most effective inhibitor in the electrochemical measurements. A more realistic endurance test was performed for 24 hours in a spray corrosion chamber. Each sample was digitalized with a scanner after specific times and the corroded area analyzed with the image-processing program ImageJ. The best inhibitor to decrease corrosion of both variations in the more realistic system was Oleoylsarcosine (O) with efficiencies of 97.4 % and 99.6 %.