Dynamic NaCl molten salt corrosion mechanism of plasma sprayed Al2O3-TiO2 modified YSZ coating

This study investigates the influence of Al 2 O 3 -20wt%TiO 2 (AT) modification on the hot corrosion resistance of YSZ coating. The YSZ coating, YSZ-AT composite coating, and YSZ/AT double layer coating were prepared using plasma spraying. An innovative dynamic corrosion method was conducted by plasma spraying NaCl under a heat flux density of 3350 kW/m 2 for 60 s, and the peak surface temperatures during corrosion exceeded 1500 °C during corrosion The results revealed that the YSZ coating suffered structural damage due to molten salt infiltration after corrosion, exhibiting a mass increase of 2.14 mg/cm 2 . In contrast, the composite coating exhibited the most severe damage due to the depletion and spalling of the AT phase, with a significant mass loss of 18.46 mg/cm 2 . However, the YSZ/AT double layer coating retained its structural integrity, experiencing only a moderate mass loss of 6.6 mg/cm 2 . The dense AT top layer (initial porosity about 0.378 %) effectively prevented molten salt penetration and acted as a sacrificial coating, reacting with the molten salt to consume corrosive media, thus demonstrating the best hot corrosion resistance.