A novel 1,2,5-thiadiazole derivative as corrosion inhibitor for mild steel in acid media

MAURO J. BANERA; CLAUDIO A. GERVASI; MARÍA V. MIRÍFICO

Santa Fe

Congreso; Congreso Internacional de Materiales y Metalurgia IBEROMAT-SAM-CONAMET 2014.; 2014

SAM-Asociación Argentina de Materiales, Sociedad Chilena de Metalurgia y Materiales (SOCHIM)

A B S T R A C T The main objective of applying the acid pickling process to steel products is the elimination of irregular conditions and the promotion of surface smoothness of the finished product. Consequently, pickling is usually the previous step to hot-dip coating or electroplating. As acidic media, HCl and H2SO4 are often used as industrial acid cleaners and pickling acids. However, since the acid also reacts with the base steel, an inhibitor is usually added to the acid solution to inhibit or lessen this acid attack on the steel itself while allowing preferential removal of the iron oxides. Among the most important organic corrosion inhibitors for acid media, heterocyclic compounds containing N, S, O atoms are considered to be the most effective. Noteworthy, the inhibition efficiency of N-heterocyclic organic inhibitors increases with the number of aromatic systems and the availability of electronegative atoms in the molecule. In this work the investigation of the behaviour of 3a,6a-difeniltetrahidro-1H-imidazo[4,5-c][1,2,5]tiadiazol-5(3H)-tiona 2,2-dióxido (ITT), previously synthesized in our laboratory, on the corrosion of mild steel in 0.5 M H2SO4 was advanced. The study was extended to 1.0 M HCl. The results obtained in both acid media were compared. Gravimetric, electrochemical, and  surface analysis measurements were performed for 24 h of immersion in the corrosive media naturally aerated and unstirred, without and with the addition of ITT in different concentrations (30 -120 µM), at 30 °C. Results show that ITT in low concentrations exerts a strong inhibiting effect on mild steel corrosion in both acid solutions, and acts as a cathodic-type inhibitor. The inhibition efficiency (EI) increases with an increase in inhibitor concentration. EI reached was ca. 94% for the higher inhibitor concentration used, being slightly higher in HCl solutions. ITT adsorption obeys the Langmuir model. Possible mechanistic pathways for the inhibition process are proposed. Observación: aceptado modalidad Póster: 15-04-2014. Aceptado para publicación en :Proceedings of the Congreso Internacional de Metalurgia y Materiales.