The effect of mesoporous silica nanocontainers incorporation on the corrosion behavior of scratched polymer coatings

A protective coating was produced by dispersing mesoporous silica nanocontainers, loaded with sodium molybdate, as corrosion inhibitor, in an epoxy layer. The corrosion properties of the composite coatings were assessed by electrochemical impedance spectroscopy. Results showed remarkable corrosion resistance of epoxy/mesoporous silica loaded with corrosion inhibitor (epoxy/MSInh) and self-healing ability of coating in the chloride medium during eight weeks of immersion. Epoxy/MSInh had the greatest Rct values for all immersion times, which could be attributed to the release of molybdate ion from the nanocontainers as well as barrier resistance of these inorganic mesoporous silica particles. This value at the first day of immersion in the chloride medium was 318.4 kΩ cm2, while it was 71.3 and 23.5 kΩ cm2 for epoxy and epoxy/mesoporous silica (epoxy/MS), respectively. Rct for epoxy, epoxy/MS, and epoxy/MSInh after the last day of immersion (56 day) was determined as 10.1, 15.9, and 24.4 kΩ cm2, respectively. Corrosion inhibitors were released from nanocontainers in response to corrosion damage in the scratched zone. Besides, the analytical investigation showed the oxidation state of Mo was (Mo (VI)), which could be attributed to the formation of Fe2(MoO4)3 or molybdenum oxides.