Advanced experimental and computational analysis of sustainable corrosion protection strategies for Al 7075 alloy

Aluminum 7075 alloy, prized for its high strength-to-weight ratio in aerospace applications, is prone to corrosion in aggressive environments, necessitating robust protection strategies. This study employs an integrated experimental and computational framework to evaluate the corrosion resistance of Al 7075 alloy under a 3.5 wt% NaCl solution with 24 h immersion. Three protective coatings anodizing, epoxy, and epoxy combined with 400 ppm tangerine peel extract (TPE) inhibitor were investigated. Experimental techniques, including Open Circuit Potential (OCP), Potentiodynamic Polarization (PDP), Electrochemical Impedance Spectroscopy (EIS), Weight Loss, Field Emission Scanning Electron Microscopy (FESEM), and Fourier Transform Infrared Spectroscopy (FTIR), were utilized to assess coating performance. Computational approaches, namely Molecular Dynamics (MD) and Density Functional Theory (DFT), were applied to explore molecular interactions and inhibition mechanisms. The epoxy coating with tangerine peel inhibitor demonstrated exceptional corrosion protection, achieving an inhibition efficiency of approximately 98 % as determined by PDP and 93 % by EIS. The standalone epoxy coating outperformed anodizing, which exhibited the lowest effectiveness among the coatings. FESEM and FTIR analyses confirmed the superior surface morphology and chemical stability of the inhibitor-enhanced epoxy coating. MD and DFT simulations elucidated the adsorption dynamics and bonding mechanisms of the tangerine peel inhibitor on the alloy surface. These results underscore the efficacy of bio-based inhibitors in developing sustainable, high-performance corrosion protection strategies for Al 7075 alloy in saline environments. • Exceptional Corrosion Inhibition: Epoxy-TPE coating delivers 98% corrosion inhibition for Al 7075 in 3.5 wt% NaCl over 24 hours, outperforming traditional coatings. • Enhanced Adsorption Mechanisms: Tangerine peel extract (TPE) bioactive compounds drive robust physisorption and chemisorption, reducing corrosion current density to 0.0001 mA/cm 2 . • Superior Surface Integrity: FESEM/EDS analyses confirm a uniform Epoxy-TPE coating with chloride penetration limited to 0.10 A%, ensuring enhanced durability. • Advanced Molecular Insights: MD/DFT simulations demonstrate a strong adsorption energy of -168.4 kcal/mol and a narrow HOMO-LUMO gap of 2.81 eV, validating molecular stability.