Salt-enhanced CMAS corrosion in marine gas turbines

In marine gas turbines, yttria-stabilized zirconia (YSZ) thermal barrier coatings (TBCs) experience severe degradation due to the combined presence of CMAS (CaO-MgO-Al 2 O 3 -SiO 2 ) deposits and sea salt. This study investigates the synergistic corrosion behavior of NaCl and CMAS on YSZ at 1300 °C. Results demonstrate that high-temperature Na + /Ca 2+ ion exchange elevates the local Ca/Si ratio, promoting Ca 3 ZrSi 2 O 9 formation and calcium diffusion into ZrO 2 grains. This process stabilizes the cubic phase and fundamentally shifts the corrosion pathway from standard dissolution-reprecipitation to accelerated grain boundary penetration. Corrosion tests reveal that a 50 wt% NaCl and 50 wt% CMAS mixture exhibits the highest aggressiveness, resulting in a penetration depth of 56.25 μm in 8YSZ after 10 h. These findings identify a salt-accelerated CMAS degradation mechanism driven by rapid ion exchange, offering critical insights for designing next-generation corrosion-resistant marine TBCs.