Lithium Carbonate-Based Hydrophobic/Self-Healing Multifunctional Coating for Magnesium Alloy AZ31B

Magnesium (Mg) alloys are valuable in the aerospace and automotive sectors, but their poor corrosion resistance limits their use. Developing self-healing coatings is essential to restoring protection after mechanical damage, and reducing the surface wettability can further enhance corrosion resistance. Here, we report the findings of the fabrication and characterization of self-healing hydrophobic PDMS-based coatings for the corrosion protection of Mg alloy AZ31B. Li2CO3 is proposed as a self-healing film-forming agent for Mg AZ31B. When incorporated into a 50 ± 5 μm PDMS-based coating, Li2CO3 improved the barrier effectiveness of the coating. The presence of this inhibitor enhanced corrosion resistance, as demonstrated by electrochemical impedance spectroscopy tests performed in a 3.5 wt % NaCl solution, which indicated a |Z|0.01Hz of approximately 1010 Ω·cm2. The scanning vibrating electrode technique validates the self-healing capability of the Li2CO3-modified PDMS coating, which showed the inhibition of corrosion propagation in artificially created defects. X-ray photoelectron spectroscopy and scanning electron microscopy studies revealed that the protective behavior of the Li2CO3-modified PDMS coating was correlated with the generation of a magnesium carbonate (MgCO3) film in the defect areas. Our research introduces a one-layer PDMS coating with durable anticorrosion, hydrophobic, and self-healing properties to protect magnesium alloys in aggressive environments.