Corrosion Inhibition of Brass in 3% NaCl Solution by Electrosynthesized Poly 4-amino-3-méthyl-1,2,4-triazole-5-thione

Abstract

This paper describes the kinetics of the electropolymerization of 4-amino-3-methyl-1,2,4-triazole-5-thiol (MTSNH) on a brass substrate in alkaline solution containing methanol. Our laboratory has developed a new synthesis strategy for MTSNH. This compound was purified and characterized by 1HNMR and 13CNMR spectroscopies. The electrochemical study was investigated using cyclic polarization, chronoamperometry, electrochemical impedance techniques and scanning electronic microscopy. The polymeric film was achieved by successive cyclic voltammetry sweep between 0 and 2.2 V at the scan rate of 10mV/s. The effect of the scan rate for 10-3 M of MTSNH in a basic solution of potassium hydroxide 0.1 M containing methanol shows that the increase of the scan rate is accompanied by the increase of the intensity of the first oxidation peak, which indicates the acceleration of the studied process. We have also shown that the monomer oxidation reaction is essentially irreversible and controlled by a diffusion process. The protective effect of the film formed on brass has been studied in a 3% NaCl. The results showed important inhibition efficiency, about 83% for 1 h of testing time.