Constructing carbon nanotube (CNTs)/silica superhydrophobic coating with multi-stage rough structure for long-term anti-corrosion and low-temperature anti-icing in the marine environment

The rough superhydrophobic surface is beneficial for capturing more gases underwater, which enhances corrosion and ice resistance for marine equipment. In this work, a PVAc-PVDF-FMCS (PPFMCS) multi-stage rough superhydrophobic coating was manufactured by a cold spraying method, significantly improving the anti-corrosion and anti-icing of aluminium alloy. The point-line structure was designed by cross-linking between multi-walled carbon nanotubes (MWCNTs) and silicon dioxide (SiO₂), which facilitated the formation of multi-stage rough surface. The porous skeleton and interfacial adhesion of the PPFMCS coating were attributed to the introduction of polyvinylidenefluoride (PVDF) and polyvinylacetate (PVAc), respectively. The PPFMCS coating had good superhydrophobicity with a water contact angle of 163.5°, while exhibiting the outstanding performance of long-term anti-corrosion and anti-icing. The |Z|_{0.01 Hz} value of the PPFMCS coating was still 9.62 × 10⁹ Ω cm² in 3.5 wt% NaCl solution for 35 days, only two orders of magnitude lower than that of the original coating, the equivalent circuits were further investigated and the metal protection is evaluated on the shore or in the deep ocean of the South China Sea. The PPFMCS coating was able to obviously delay icing for 5 min at −20 °C, the ice adhesion of its surface was as low as 85.5 kPa. The icing phase transition was analysed by a thermodynamic method. The coating also had good stability and drag reduction performance. This high-performance coating based on point-line structural design is expected to have practical applications in marine transportation, oil exploration and polar exploration.