Dynamic visualization for stress-induced crack initiation and resulted corrosion expansion in carbon quantum tailored epoxy coating

Metal/coating systems of marine energy equipment exposed to both environmental erosion and mechanical loads are susceptible to microdamage and localized corrosion, resulting in premature failure of the metal equipment and potentially catastrophic incidents. In-situ monitoring of coating cracking and interfacial corrosion is critically important for health status yet remains a challenge to realize. Herein, a facial and robust damage-sensing strategy based on dynamic fluorescence of carbon quantum dots is proposed to construct smart anticorrosive coatings with hierarchical damage visualization capabilities. Through integrating fluorescent carbon quantum dots (CDs) into an epoxy matrix, the stress-induced crack initiation and propagation dynamics on coating are visually indicated by the intensified fluorescence. Meanwhile, localized metal corrosion at the damaged interface is manifested by ferric ion-induced fluorescence quenching of CDs. The damage responsiveness of smart coating under sustained load and instantaneous impact stress is demonstrated by the dynamic “on-off” behaviors of interfacial fluorescence. Moreover, the toughness and the ability to resist crack generation and corrosion inhibition of coating are significantly enhanced by regulating resin molecular structures. In addition, electrochemical in-situ evaluation was used to assess the failure of coatings in metal/coating systems under stress. This smart coating with hierarchical damage-warning and mechanical properties opens up a new way for on-site, large-scale, and real-time monitoring of microcrack generation and corrosion pits in marine structural components.