Investigation of adsorption and effect inhibition thiourea on the corrosion behavior of 6061-T6 aluminum alloy in nitric acid environment

In this research, corrosion inhibition of 6061-T6 aluminum alloy in nitric acid by inhibitor of thiourea in two type of solution using tests electrochemical and quantum mechanical calculations have been investigated. Cyclic polarization and electrochemical impedance results showed that with increasing concentrations of inhibitors, pitting potential rosed and sensitivity to pitting diminishes. Anodic and cathodic polarization curves showed that the inhibition was mixed type inhibitors and the inhibition efficiency increases with increasing inhibitor concentration. Inhibitor adsorption on the surface from the Langmuir isotherm can follow. Adsorption free energy calculations revealed that corrosion inhibition is type of physical adsorption. Quantum chemical calculations showed that the inhibitor adsorption on the alloy surface through nitrogen and sulfur atoms as well as π electrons done and reduces the energy difference between the HOMO and LUMO significant role has increasing inhibition efficiency.