Polymer-based electromagnetic wave-absorbing (EWA) coatings that can effectively dissipate electromagnetic radiation are in high demand. While researchers on the development of lighter and more efficient EWA coatings have been carried out extensively, there is limited information on their durability and the underlying degradation mechanisms. In this work, epoxy (EP)/flake carbonyl iron powder (FCI) coatings were selected as the model EWA coating. UV aging experiments of specimens were conducted up to about 240 h to study the effects of additional FCI on the photo-oxidative behaviors of coatings. The evolutions in the surface topography, chemical structure, hydrophilicity of aged coatings were systematically studied by Scanning electron microscopy (SEM), Laser scanning confocal microscopy (LSCM), Fourier transform infrared spectroscopy (FTIR), and static contact angle measurement, and further combined with micro-FTIR to investigate the degradation diffusion behavior from the exposed surface to the bulk of coatings. The results showed that the addition of FCI significantly accelerated the photo-oxidation of EP coatings, which was attributed to the corrosion of FCI during aging and the concomitant photo-catalytic degradation effects of its corrosion products. Moreover, the cross-sectional analysis revealed a non-uniform distribution of EP degradation species across the thickness direction, while it is interesting to find that the degradation depth of EP/FCI coating was lowered compared with that of pure EP coating, which could be due to the UV blocking effect of FCI. This work clearly revealed the underlying mechanisms for the distinct dependence of surface and cross-sectional degradation of coatings on the incorporation of FCI, which has laid crucial groundwork for durability evaluation and performance optimization of EWA coatings.

能够有效消散电磁辐射的聚合物基电磁波吸收 (EWA) 涂层的需求量很大。虽然研究人员对开发更轻、更高效的 EWA 涂层进行了广泛的研究，但关于其耐久性和潜在降解机制的信息有限。在这项工作中，环氧树脂（EP）/片状羰基铁粉（FCI）涂层被选为模型 EWA 涂层。样品的紫外线老化实验进行了大约 240 小时，以研究额外的 FCI 对涂层光氧化行为的影响。通过扫描电子显微镜 (SEM)、激光扫描共聚焦显微镜 (LSCM)、傅里叶变换红外光谱 (FTIR)、和静态接触角测量，并进一步结合 micro-FTIR 来研究从暴露表面到大部分涂层的降解扩散行为。结果表明，FCI的加入显着加速了EP涂层的光氧化，这归因于FCI在老化过程中的腐蚀及其腐蚀产物的伴随光催化降解作用。此外，横截面分析显示 EP 降解物种在厚度方向上的分布不均匀，而有趣的是发现 EP/FCI 涂层的降解深度与纯 EP 涂层相比降低，这可能是由于 FCI 的紫外线阻挡作用。