Organic coating failure and monitoring in atmospheric corrosion: from mechanisms to applications

Abstract

The failure of organic coatings protecting metal structures in aerospace and marine engineering under atmospheric corrosion has become a critical threat to structural safety. The NACE report indicates that 38 % of global corrosion costs stem from coating failure. This data is directly associated with the accelerated failure of the coating’s physical barrier caused by Cl⁻ in the marine atmosphere (diffusion coefficient D ≈ 5 × 10⁻¹¹ cm²/s). This review focuses on organic coatings for metal structures and constructs a systematic scenario-mechanism-technology-model framework: ① Analyze three core environmental characteristics—electrochemical catalytic effects of SO₂/NO_x in industrial atmospheres, deliquescence-crystallization cycles of Cl⁻ in marine atmospheres, and synergistic effects of hypoxia, low temperature, and intense UV in aerospace high-altitude environments; ② Reveal multi-scale failure mechanisms: molecular-level degradation (e.g., ester bond hydrolysis in epoxy resins, C-F bond cleavage in fluorocarbon coatings), microscale defect propagation, and macroscopic delamination, establishing a medium penetration-interface reaction-structural deterioration failure clock model; ③ Compare monitoring technologies (EIS has a 12 % false negative rate in marine environments, SKP achieves 89 % accuracy in aerospace interface debonding early warning) and evaluate prediction models (Arrhenius empirical model shows > 20 % error at high temperatures, LSTM-GARCH model achieves < 10 % error under multi-factor conditions). Key bottlenecks identified include: lack of cross-scale modeling for multi-factor synergistic failure, engineering obstacles for self-healing smart coatings, and heavy data dependence of AI models. Future research should focus on quantifying physical-electrochemical coupling mechanisms and integrating fiber optic sensing with digital twins to provide lifecycle protection for high-end equipment coatings.