Marine anticorrosion and antifouling assessment of multifunctionalized hybrid sol-gel coatings

The corrosion and fouling of steel surfaces are major problems affecting the infrastructure of most industries, especially the oil and gas industries. The application of barrier coatings is one of the most widely used methods for mitigating these metal-loss causing problems. In particular, multifunctional hybrid sol-gel coatings are a very promising alternative to the currently used commercial toxic anticorrosion/antifouling coatings. This study describes the functionalization of a hybrid sol-gel polymeric coating with MOLY⁽¹⁾ or ZAPP⁽²⁾ corrosion inhibitors and viable endospores of Bacillus licheniformis isolate (B6). The resulting functionalized coatings were applied to S36 grade mild steel substrate and their corrosion protection properties have been evaluated in the lab using electrochemical impedance spectroscopy (EIS) technique as well as scanning electron microscopy and visual observations. The field testing of the anticorrosion and antifouling properties of all coatings was also conducted by the in-situ exposure of the coated panels to seawater at a marine exposure site. Both lab and field testing results of all coated samples indicated that the biotic systems (containing bacterial spores) inhibited corrosion and fouling more than the abiotic (without bacterial spores) ones due to varying adhesion, barrier and antimicrobial properties of these coatings. It revealed also that abiotic and biotic coatings doped with Moly inhibitor have demonstrated excellent corrosion and fouling inhibition properties comparing to ZAPP coatings and the Corro⁽³⁾ commercial coating.