Self-reporting coatings for autonomous detection of coating damage and metal corrosion: A review

This paper provides an overview on the research progress of self-reporting corrosion protection coatings, which can autonomously indicate coating damages and metal corrosion at early stages. Typical sensing species in selfreporting coatings include fluorescent indicators, color indicators, and mechanically triggered indicators. Upon coating damage and corrosion initiation on the underlying metal substrate, the indicators are released and activated by either pH variation or the presence of metallic cation due to corrosion and other physicochemical reactions within the local defect. In this way, self-reporting coating systems can express strong fluorescence signals or color change to highlight the coating failure. The sensing principles, influencing factors, coloring performances, advantages and drawbacks of different types of self-reporting coatings are discussed. Incorporation of indicators into micro- or nanocapsules is highlighted to enhance their reliability as well as to optimize the fluorescence/coloration performance. In addition, dual-functional coatings combining both the self-reporting and self-healing capacities are introduced, which can not only detect the coating damages but also autonomously recover the barrier property. The development of self-reporting corrosion protection coatings thus holds great potential to improve the safety and lifetime for materials in various industrial applications.

Automated summary

This paper provides an overview of self-reporting corrosion protection coatings, discussing their sensing principles, influencing factors, advantages and drawbacks. The incorporation of indicators into micro- or nanocapsules is highlighted to enhance their reliability and performance. Introduction of dual-functional coatings combining self-reporting and self-healing capacities shows great potential in improving material safety and lifetime in various industrial applications.