Sea salt enhances the CMAS corrosion of thermal barrier coating

Molten deposits originating from siliceous debris such as airborne dust, sand, or volcanic ash entrained into the intake air, represent a critical threat to the durability of thermal barrier coatings (TBCs). Such systems are usually approximated experimentally by on calcium-magnesium aluminosilicate melts (CMAS). While extensive studies have elucidated CMAS corrosion from the terrestrial sources listed above, the role of sea salts – ubiquitous in costal environments – remains unclear. Here, we investigate the effect of sea salt from four China sea regions on CMAS corrosion of TBCs. By integrating high-temperature wetting behavior, microstructural analysis and first-principles calculation, we demonstrate that the presence of sea salt accelerates TBC degradation and that its concentration governs its impact on CMAS melt fluidity, spreading, and degradation of TBCs. An optimized CMAS model is proposed to guide future corrosion assessments and design TBCs with improved tolerance to salt-accelerated degradation under coastal service conditions.