Hydrophobic Silica Coating for Anticorrosion and Antibacterial Protection of Food Contact Metals

Abstract Corrosion of metal materials that come into contact with food causes huge economic losses and poses hidden health risks. Metal coating is an effective mean of corrosion prevention. Among the metal coatings, silica‐based coatings have significant advantages over ordinary plastic coatings, such as environmental friendliness, low toxicity, and strong adhesion. This paper developed a hydrophobic silica coating, based on a self‐catalytic sol‐gel polymerization mechanism, which is beneficial to form a substantial coating easily. The coating exhibited >90° water contact angles and complete prevention of bacterial adhesion on multiple metals (brass, galvanized steel, Q235, and aluminum alloy). In corrosion resistance tests involving copper sulfate and lead acetate pitting on coated surfaces of brass, galvanized steel, and Q235, the coating delayed the occurrence of pitting corrosion by dozens of times compared to bare metals. In contrast, due to aluminum alloy's inherent superior oxidation resistance, the change was not significant. After 336 h water immersion, coated metals retained structural integrity with negligible corrosion. Besides, such silica coatings are able to prevent bacterial adhesion on the metal surface, displaying antibacterial feature. This hydrophobic silica coating demonstrates significant application potential in the field of corrosion and antibacterial protection for metals.