A review of high-quality epoxy resins for corrosion-resistant applications

Corrosion is a significant challenge in many practical applications, leading to the deterioration of metal infrastructure and equipment. A literature review indicates that various epoxy resins (ERs) and epoxy phenolic resins (EPRs) based coatings are available and are effectively applied on steel and aluminum surfaces for protection against a corrosive environment. The corrosion-resistant performance of ERs and EPRs can be further improved by incorporating numerous chemical compounds through improved bonding, such as inorganic compounds and carbon-based materials, e.g., zinc oxide (ZnO), titanium dioxide (TiO₂), silicon dioxide (SiO₂), carbon fiber, carbon nanotube (CNTs) and graphene oxide (GO). Surface heterogeneity (surface pores) of coatings contributes to reduced corrosion protection as corrosion species can diffuse to these inconsistencies and break the coating structure of the organic coating. However, after over a hundred years of research and development, the degradation/failure mechanism of organic coatings is still under study. This paper provides an overview of the current state-of-the-art knowledge of the numerous protective organic coatings and coating approaches and examines coating performance and mechanism for the coating degradation and failure in a corrosive environment. Finally, a summary is presented on the understanding of the mechanisms and challenges associated with, and critical factors influencing, coating durability and predictive formulation against coating damage.