Anodic galvanostatic polarization of AA2024-T3 aircraft alloy in conventional mineral acids

The present study is devoted to the determination of the impact of the anodization of AA2024-T3 alloys in HCl, HNO₃, H₂SO₄ or H₃PO₄ on the samples' surface morphology and properties. Subsequent systematic assessments were performed by Scanning Electron Microscopy (SEM), Energy Dispersion X-Ray Spectroscopy (EDX) and X-ray Photoelectron Spectroscopy (XPS). These observations were combined with Linear Voltammetry (LVA) and Electrochemical Impedance Spectroscopy (EIS) after 48 and 168 h of exposure to a 3.5% NaCl model corrosive medium. The main result is, that completely different effects were observed in accordance to the acid used. It was established that the monoprotonic acids have a deep destructive effect due to dissolution of the alloy components, whereas the polyprotonic ones possess either indistinguishable influence, or surface film formation. - Highlights: • AA2024 was polarized anodically in 15%_wt acid solutions at 15 mA cm⁻² for 2 h. • Four mineral acids were selected for investigation: HCl, HNO₃, H₂SO₄ and H₃PO₄. • SEM, EDX and XPS were applied for morphological description. • Electrochemical characterizations were performed by EIS and linear voltammetry. • The acid used predetermines completely different interaction with the AA2024 alloy.