Combined atomic-scale/DFT-theoretical simulations and corrosion protection study of AA2024-T3 in 3.5% NaCl by phenolphthalein derivatives: Surface characterization (FT-IR, FT-RAMAN, and SEM)

This work investigates the effectiveness of two organic inhibitors, CH3O-φ-OCH3 (P3) and bzO-φ-Obz (P4), in preventing corrosion of aluminum alloy 2024-T3 in a 3.5% NaCl solution. The study employs a combination of experimental and theoretical research methods to gain a comprehensive understanding of the corrosion inhibition behavior. Density functional theory (DFT) studies and molecular dynamics (MD) simulations provide atomic-level insights into the resistance mechanism and the influence of the molecular structures of P3 and P4 on corrosion inhibition. The potentiodynamic polarization experiments (PDP) confirm that the studied compounds are mixed-type inhibitors. At a concentration of 10⁻⁴ M, P3 and P4 exhibit impressive inhibition efficiencies of 87.5% and 92.5%, respectively. FTIR and Raman spectroscopy were utilized to show that an adsorbent protective layer was formed on the surface of the aluminum when it was immersed in an inhibited solution. The scanning electron microscopy (SEM) morphology analysis indicates that the presence of P3 and P4 inhibitors effectively reduces corrosion on the surface of the AAl 2024 alloy. Furthermore, energy-dispersive X-ray spectroscopy (EDS) analysis confirms the formation of a chemical particle coating on the surfaces of the Al alloy. Electrochemical impedance (EIS) measurements of total resistance bias (Rp) further demonstrate the superior corrosion resistance of the inhibitors, as the resistance increases with inhibitor concentration. These findings highlight the strengths of this work in providing a comprehensive understanding of the corrosion inhibition mechanism and the excellent performance of P3 and P4 as inhibitors for aluminum alloy 2024-T3 in a NaCl environment.