A novel high corrosion-resistant and superhydrophobic MAO-30/PA/VTES composite coating on Cu 15Fe alloy for long-term corrosion protection

The copper (Cu) alloys are prone to severe corrosion in marine environments. In this work, we successfully develop a novel high corrosion-resistant and superhydrophobic MAO-30/PA/VTES composite coating on Cu15Fe alloy for long-term corrosion protection. The composite coating, with a corrosion rate of 0.00001 mm/y and a water contact angle of 152.7°, presents significant advantages over most Cu alloys modification methods to date. Benefiting from the modification with phytic acid (PA) and vinyltriethoxysilane (VTES), the corrosion current density of the composite coating remains 2.14 × 10−10 A·cm−2 even after 168 h of immersion in 0.6 M NaCl, which is four orders of magnitude lower than Cu15Fe substrate (5.68 × 10−6 A·cm−2). The exceptional long-term corrosion resistance of the composite coating is attributed to the physical barrier effect of the micro-arc oxidation (MAO) layer, the superhydrophobic characteristics and sealing effect of the PA/VTES film layer, and the chelating effect of the phytic acid. Developing the composite coating introduces a new approach to protecting Cu alloys from corrosion in marine environments.