MULTIFUNCTIONAL, SMART AND ENVIRONMENTAL FRIENDLY ANTICORROSIVE COATINGS BASED ON NANOCONTAINERS

摘要

Assorted functionalities can be incorporated into organic coatings for corrosion protection. Among them, the three that are probably considered the most relevant, promising and with possibilities to be applied at industrial and commercial scale for corrosion protection applications are: a) encapsulation of self-healing agents in nanocontainers, b) encapsulation of corrosion inhibitors in nanocarriers and c) ion-exchange pigments. Even though smart functional coatings offer a significant advantage compared to passive classic systems, due to the improvements in durability and effectiveness because they act locally and exclusively under demand, the actual trends try to go further, looking for the development of multifunctional coatings, i.e., the combination of different functionalities in the same paint system. This can be achieved within the same layer of the protective system or adding different functionalities to different layers. In the present study, new multifunctional and smart anticorrosive coatings that combine high protective efficiency and lower environmental impact have been designed, developed and evaluated. As functional protective systems, Melamine-Urea-Formaldehyde (MUF) nanocapsules containing 5-ethylidene-2-norbomene (ENB) as self-healing agent, sodium phosphomolybdate as corrosion inhibitor encapsulated in mesoporous silica nanoparticles (MSN), as well as, Hydrotalcite/Vanadate (HT/V) as ion-exchange pigment have been considered. The smart containers have been incorporated to hybrid sol-gel coatings and applied to mild steel substrates. Artificial mechanical microdefects have been prepared in the coating in order to study the anticorrosive behaviour in the affected area by means of different localised electrochemical techniques. The anticorrosive mechanisms involved for each protective agent incorporated into the multifunctional coating systemhas been also in-depth studied.