Abstract
The corrosion of single crystal pure iron in 3.5% NaCl solutions and its inhibition by 3-amino-5-mercapto-1,2,4-triazole (AMTA) have been studied using in situ and ex situ Raman spectroscopy, cyclic voltammetry (CV), open-circuit potential (OCP), potentiodynamic polarization (PDP), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS) measurements. CV experiments indicated that the iron electrode in the chloride solution alone showed an anodic peak at ∼−650
mV after the 5th cycle shifted to ∼−610
mV after the 20th cycle; another cathodic peak appeared at ∼−990
mV. In the presence of 1.0
mM AMTA, these two peaks shifted to ∼550 and −1050
mV, respectively. OCP, PDP, CA and EIS revealed that the presence of AMTA and the increase of its concentration move the corrosion potential to more positive values and decrease both the corrosion current and corrosion rate. This effect also increases with increasing the immersion time of iron electrode to 24
h in the test electrolyte. In situ and ex situ Raman investigations confirmed that the addition of AMTA molecules to the chloride solution strongly inhibits the iron corrosion through their adsorption onto the surface blocking its active sites and preventing its corrosion.