Corrosion inhibition performance of two plant extracts and sodium silicate compound on AA2024-T3 aluminum alloy in NaOH medium

In this paper, corrosion inhibition performance of Helianthus tuberosus L extracts(HTLE) and Poria cocos extracts(PCSE) alone and compounded with Na 2 SiO 3 in 0.01 mol L −1 NaOH solution on AA2024-T3 aluminum alloy was investigated by weight loss, electrochemical impedance spectroscopy, potential polarization, atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS), quantum chemical calculations and molecular dynamics simulations. Infrared spectroscopy was used to study the main active components in both extracts. The results revealed that when the two extracts were utilized separately, the corrosion inhibition impact was insignificant. However, when compounded with Na 2 SiO 3 , the corrosion inhibition efficiency was greatly enhanced. Fixing the concentration of Na 2 SiO 3 at 610 mg L −1 , the inhibition effectiveness rose with the increase of the concentration of the extracts, and when the concentration of HTLE, PCSE were 800 mg L −1 and 1000 mg L −1 , respectively, the inhibition efficiencies could reached approximated 98 %. The two compounds were anodic-dominant hybrid corrosion inhibitors. AFM and XPS analysis revealed that the two compounds could successfully adsorb on the aluminum alloy surface, protecting the metal from corrosion. Theoretical simulations were conducted by selecting the three major components from each of the two extracts. Quantitative chemistry calculations indicated the accepted and donated electron groups of the major components. Molecular dynamics simulations show that the primary components compounded with Na 2 SiO 3 have a higher negative adsorption energy than their action alone.