Designing attapulgite-based self-healing superhydrophobic coatings for efficient corrosion protection of magnesium alloys

Magnesium (Mg) and its alloys are susceptible to corrosion, which affects their large-scale applications. The traditional superhydrophobic coatings for corrosion protection of Mg substrates are particularly fragile and easily damaged after prolonged exposure to harsh conditions. Herein, a superhydrophobic ODA/PDA/APT-Ce3+ (OPA-Ce3+) coating with corrosion inhibition and self-healing properties was proposed to prevent corrosion of Mg alloy via combining the cerium nitrate loaded attapulgite (APT), polydopamine (PDA) and octadecylamine (ODA). Once the OPA-Ce3+ coating was corroded, the Ce3+ adsorbed by the APT were released to form insoluble cerium oxide and hydroxides, thereby inhibiting the penetration of the corrosive substance and preventing further occurrence of corrosion. Furthermore, the OPA-Ce3+ coating exhibited favorable self-healing ability against chemical damage, which could recover its superhydrophobicity under solar exposure after O2 plasma etching. The impedance modulus (|Z|0.01 Hz) of OPA-Ce3+ coating was about 3 orders of magnitude higher than that of Mg substrate after being exposed to 3.5 wt% NaCl solution for 15 days, showing outstanding long-lasting anticorrosion performance. Moreover, the abrasion resistance and chemical stability of the as-fabricated coating were also excellent. This work is expected to provide a new perspective for preparing cost-effective and durable anticorrosion coating on metal substrates.