Designing a Hierarchical FG-SiC Reinforced Fluoropolymer Coating for Integrated Corrosion Protection, Wear Resistance and Heat-Transfer Enhancement

How to synergistically address the issues of corrosion resistance, wear resistance and heat transfer of heat-exchange equipment has always been a bottleneck limiting the deep recovery of flue gas waste heat. Achieving their integrated synergy within fluoropolymer-based protective coatings continues to pose a significant challenge. Herein, a hierarchical fluoropolymer composite coating was constructed by combining functional filler engineering with a layered pore-structured architecture. A fluorinated graphene-silicon carbide (FG-SiC) hybrid filler was synthesized via dopamine-assisted modification to enhance barrier performance, wear resistance, and thermal transport within the fluoropolymer matrix, while also contributing to a roughened low-surface-energy surface favorable for dropwise condensation. Meanwhile, electrophoretic deposition and electrostatic spraying were integrated to fabricate a graded coating with a pore-induced interlocking interface, enhancing structural stability. The optimized coating maintained an impedance modulus above 2.5 × 1010 Ω·cm2 during long-term acidic immersion, with the corrosion current density reduced by more than 5 orders of magnitude. The incorporation of FG-SiC also enhanced wear resistance under mechanical abrasion, with the mass loss reduced by nearly 30% after 100 sandpaper wear cycles. In addition, the stable hydrophobic surface promoted dropwise condensation, resulting in a steam-side convective heat-transfer coefficient more than twice that of the bare tube. This integrated filler–structure design provides an effective approach for multifunctional fluoropolymer coatings in flue gas waste heat recovery.