Abstract
In this study, the inhibition of corrosion reactions on copper surface in open to air solutions of 0.5 M NaCl and 0.5 M of HCl by 5-ethyl-1,3,4-thiadiazol-2-amine (ETDA) was investigated. The study was carried out by using a combination of electrochemical techniques, such as potentiodynamic polarization, chronoamperometry; in addition to electrochemical impedance spectroscopy (EIS) and weight-loss (WtL) measurements. Polarization curves showed that the presence of ETDA and the increase of its concentration in chloride media decrease the corrosion current density and corrosion rate and enhance the polarization resistance for copper. Chronoamperometric and EIS investigations revealed that ETDA molecules decrease the pitting and uniform corrosion of copper through decreasing the absolute currents and increasing the surface and polarization resistances of copper in both NaCl and HCl solutions. This effect was found to remarkably increase with increasing the concentration of ETDA from 1.0 mM to 5.0 mM. WtL results depicted that NaCl and HCl molecules aggressively attack copper causing its fast dissolution with time. WtL data proved also that the presence of ETDA and the increase of its concentration highly preclude the dissolution of copper. The calculated inhibition efficiency of ETDA recorded higher values for copper in NaCl solutions than HCl ones.