Investigation of 4-Amino-3-Hydrazino-5-Mercapto- 1,2,4-Triazole as Corrosion Inhibitor for C38 Steel in Hydrochloric Acid Medium

The inhibition effect of 4-Amino-3-hydrazino-5-mercapto-1,2,4-triazole (AHMT) against the corrosion of C38 steel in 1 M HCl solution was studied by weight loss, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization. Inhibition efficiency increased with inhibitor concentration and it attains an efficiency of more than 87% at 10^-2 M at 308K. Polarization curves show that AHMT is a mix-type inhibitor. As the inhibitor concentration increased, the charge transfer resistance of C38 steel increased and double layer capacitance decreased. The adsorption of AHMT molecules on the C38 steel surface obeys Langmuir adsorption isotherm. The adsorption free energy of AHMT on C38 steel (-34.88 kJ / mol) involves two types of interaction, chemisorption and physisorption of the inhibition on the metal surface. The results obtained from the different methods are in good agreement.