Beyond graphene: Anticorrosion performance of fluorographene-filled perfluoroalkoxy alkane composite coatings for condensing heat exchanges

Perfluoroalkoxy alkane (PFA) is a promising coating material for corrosion protection in concentrated sulfuric acid environments owing to its outstanding chemical stability, but the poor barrier property greatly limits its applications. Herein, graphene and fluorographene reinforced PFA composite coatings (Gr/PFA & FG/PFA) were designed and investigated. Our results reveal that FG/PFA exhibits more remarkable corrosion protection performance and barrier property than Gr/PFA. Graphene and fluorographene increase the crystallinity of composite coatings to 43% and 44.3% at 0.75 vol% nanofiller contents, respectively. As a result, the fillers improve the barrier property of PFA resin via a dual-action mechanism: acting the physical barrier and enhancing the crystallinity of the resin matrix. Besides, the chemical stability test further reveals that the FG/PFA exhibits a superior oxidation resistance than Gr/PFA. The |Z|0.01 Hz value of the composite coating with 0.75 vol% fluorographene can still reach 1011 Ω•cm2 after immersion in 85 wt% H2SO4 solution under 180 °C for 30 days. We believe that the FG/PFA has broad application prospects in the field of preventing low-temperature dew point corrosion of sulfuric acid for flue gas waste heat recovery utilization.