Sprayable Graphene Oxide-Based Superhydrophobic Coating with High Mechanical/Chemical Stability and Self-Healing Performance for Corrosion Protection of Mg Alloys

This study introduces a robust, self-healing superhydrophobic coating for magnesium (Mg) substrates, leveraging the synergistic effects of MQ organosilicon polymer, octadecylamine (ODA), polydopamine (PDA), and copper-loaded graphene oxide (GO). The coating exhibits exceptional superhydrophobicity, outstanding stability in harsh environments, superior resistance to smudging, and effective self-cleaning capabilities. Electrochemical impedance spectroscopy (EIS) in 3.5 wt % NaCl solution demonstrates an impedance modulus (|Z|) at f = 0.01 Hz and polarization resistance (R_p) of 3.49 × 10⁸ Ω cm² and 3.88 × 10⁸ Ω cm², respectively, 7 orders of magnitude higher than AZ31B. After 35 days of immersion, |Z|_{f=0.01 Hz} and R_p remain at 3.97 × 10⁷ Ω cm² and 4.63 × 10⁷ Ω cm², respectively, highlighting long-term corrosion protection. In cases of damage or corrosion, the dynamic coordination of PDA-Cu²⁺ enables self-healing, fully recovering visible coating defect up to 10 μm in width within 24 h in 3.5 wt % NaCl solution. This work presents a promising approach for durable, self-healing superhydrophobic coatings with exceptional mechanical and chemical stability.