Sustainable valorization of rice husks into silicon carbide for high performance anti-corrosion coatings

High-value valorization of discarded rice husk remains insufficient at present. Conventional commercial silicon carbide (SiC) suffers from high production cost, restricting its large-scale application in anticorrosion coatings. Herein, rice husk-derived and silica-derived SiC were fabricated via a sodium hydride-aluminum chloride (NaH–AlCl3) molten salt method with subsequent calcination at 1600 °C. The two types of as-prepared SiC and commercially available SiC were used as fillers to prepare epoxy anticorrosion coatings on Q235 steel substrates. Fillers were characterized by SEM and TEM, and coating anti-corrosion behaviors were systematically assessed by salt spray and electrochemical tests. Experimental results reveal rice husk-based SiC consists of uniform nano-sized particles. The CP-RH-SiC coating exhibited a low-frequency impedance modulus on the order of 105 Ω cm2, indicating corrosion protection close to, but slightly lower than, that of the commercial SiC coating. Compared with industrial SiC, biomass-derived SiC serves as a promising filler for effective anticorrosion coatings. This work provides a feasible route to recycle agricultural rice husk and realize its high-value utilization.