In-Situ Modification of SiO2 Coatings on Steel Plates for Water Repellent Applications

This study investigates the in-situ modification of cristobalite SiO₂ coatings on steel plates to enhance surface properties, focusing on developing hierarchical structures for water-repellent applications. Cristobalite SiO₂ was synthesized from silica sand via co-precipitation and combined with methyltrimethoxysilane through in-situ modification using sol-gel methods. Samples were prepared with varying cristobalite SiO₂ concentrations of 0, 1.5, 3, 4.5, and 6 wt%. XRD characterization confirmed the coexistence of crystalline and amorphous phases, while SEM indicated changes in particle size and morphology due to cristobalite SiO₂ addition. FTIR analysis identified Si–O–Si asymmetric stretching bonds, and AFM demonstrated the formation of hierarchical micro-submicron structures with enhanced surface roughness. The roughness factor of the sample coatings was determined through calculations based on the AFM topographical data. Hydrophobicity analysis using water contact angle (WCA) measurements showed improved performance with increasing cristobalite SiO₂ content, achieving a maximum WCA of 132.6 ± 4.1°. The coated steel plates exhibited excellent hydrophobic properties, offering promising potential for practical applications in water-repellent technologies.