Corrosion and fouling protection performance of biocide-embedded hybrid organosiloxane coatings on mild steel in a saline medium

This work assessed the anticorrosion and antifouling properties of a novel sol-gel derived hybrid coating functionalized with 5 different organic and inorganic biocides. FTIR and NMR analysis of the newly synthesized polymeric base material confirmed the photo-induced organic polymerization of the allyl groups in the allyltrimethoxysilane precursor of the polymer and the inertness of the allyl groups in the allyl glycidyl ether precursor. The parent coating and biocide-embedded coatings were applied on mild steel sheets, cured with UV light, and subjected to thermal, morphological and electrochemical characterization. The cured coatings were thermally stable, and their hydrophobicity increased after immersion in a saline medium, owing to further polymer crosslinking. According to lab-based electrochemical and visual evaluations of the corrosion protection performance of the different formulations, the coating embedded with Irgarol and MOLY-white 101 had an improved performance, compared with the formulations with the other added biocides. Field testing results from the coated samples were consistent with the lab results; i.e., some biocides positively affected the anticorrosion and antifouling behavior of the hybrid coatings, whereas other biocides negatively affected the newly developed hybrid coating. The methodology reported here holds promise for the development of multifunctional hybrid sol-gel coatings for mild steel substrates with interesting anticorrosion and antifouling activities in saline.