Corrosion-Fatigue Performance of Hard Anodized and MAO-Coated 2024-T3 and 7075-T6 Aerospace Al Alloys

In the present study, micro-arc oxidation (MAO) coatings were deposited on shot peened high-strength aerospace aluminium alloys namely 2024-T3 and 7075-T6. The comparative corrosion-fatigue performance was evaluated in 3.5 wt.% NaCl corrosion environment for bare, hard anodized and SP + MAO (prior shot-peened and MAO) coated Al alloys. Also, the corrosion behavior of bare and SP + MAO coated Al alloys was assessed through potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) tests. In addition, SP + MAO coatings were characterized for the phase composition, surface/cross-sectional morphologies and surface roughness. Furthermore, the corrosion-fatigue fractured features of coatings were examined to understand the failure mechanisms. The SP + MAO coatings deposited on Al alloys possess superior corrosion-fatigue life as compared to the bare and hard anodized conditions.