Anti-Corrosion superhydrophobic coating of Hexadecyltrimethoxysilane-Functionalized Magnetite-silica for superior steel protection

Abstract This work presents the synthesis of a superhydrophobic anti-corrosion coating made of magnetite-coated silica modified with hexadecyltrimethoxysilane (Fe 3 O 4 @SiO 2 -HDTMS) to improve a commonly used epoxy coating. This modification aims to provide superior protection for steel surfaces against moisture and oxygen present in humid air. The coating was analyzed in terms of its structure, chemical composition, particle morphology, water contact angle (WCA), adhesion strength, flexibility, and resistance to mechanical impact. The anti-corrosion performance of the Fe 3 O 4 @SiO 2 -HDTMS coating was evaluated using salt spray, salt immersion tests and potentiodynamic polatization measurement. Fourier transform infrared spectroscopy (FTIR) analysis confirmed the succesful incorporation of HDTMS, Fe 3 O 4 , and SiO 2 . X-ray Diffraction (XRD) patterns indicated diffraction peaks consistent with a combination of crystalline Fe 3 O 4 and amorphous SiO 2 structures. Transmission electron microscopy (TEM) imaging revealed a core–shell morphology, with an average particle size of 21.93 ± 5.96 nm. The coating was applied via spray coating using an optimal molar ratio of Fe 3 O 4 :SiO 2 : HDTMS at 0.0025:0.005:0.003, resulting in a hydrophobic surface with a WCA of 154.33 ± 0.58°. The coating demonstrates excellent adhesion strength, flexibility, and impact resistance. The measured corrosion rates under artificial seawater are 0.0059 mpy, indicating that the Fe 3 O 4 @SiO 2 -HDTMS coating provides effective protection for the infrastructure against corrosion, especially for steel in marine environments.