Spectroscopic and DFT investigations on the corrosion inhibition behavior of tris(5-methyl-2-thioxo-1,3,4-thiadiazole)borate on high carbon steel and aluminium in HCl media

Abstract

The effect of tris(5-methyl-2-thioxo-1,3,4-thiadiazole)borate (HB(mtda^Me)₃) on the corrosion of high carbon steel (HCS) and aluminium (Al) in HCl media has been examined by Electrochemical Impedance Spectroscopy (EIS), polarization (Tafel), Scanning Electron Microscopy (SEM), X-ray Photoelectron Spectroscopy (XPS), Electronic spectroscopy and adsorption kinetics methods. The polarization studies show that HB(mtda^Me)₃ acts as a cathodic inhibitor for HCS, while it is a mixed type inhibitor of predominantly the cathodic reaction in Al. The inhibition efficiency of the compound is very high and the SEM and XPS results have revealed that HB(mtda^Me)₃ is adsorbed on the HCS and Al surface. The adsorption of HB(mtda^Me)₃ on the HCS and Al surface obeys the Langmuir adsorption isotherm. DFT calculations were used to gain insight into the structural and electronic properties in relation to the inhibition efficiency.