CMAS Corrosion Behavior of Plasma‐Sprayed Thermal Barrier Coatings With Thin‐Wall Hollow Spherical YSZ

ABSTRACT Molten calcium–magnesium–alumino–silicate (CMAS) corrosion is a primary failure mode of thermal barrier coatings (TBCs) during service. To enhance the CMAS resistance of conventional atmospheric plasma sprayed (APS) yttria‐stabilized zirconia (YSZ) coatings, this study employed thin‐walled hollow spherical (THS) YSZ powder to fabricate TBCs. Owing to its superior melting characteristics, a dense and uniform coating structure containing noninterconnected pores was successfully obtained. The degradation behavior of APS TBCs prepared from three powder types—THS, conventional sintered‐crushed (SC), and nanoagglomerated (NA), differing in morphology and grain sizes—was systematically compared after CMAS corrosion at 1240°C for 0.5, 8, and 16 h. The results indicate that the THS‐YSZ coating exhibited the most superior resistance to CMAS corrosion, with a continuous corrosion depth of only about 6 µm after 16 h. In contrast, the SC‐YSZ coating underwent severe degradation with extensive spallation and disintegration, reaching a maximum corrosion depth of 81 µm, while the NA‐YSZ coating also suffered significant corrosion with a penetration depth of 37 µm. This work demonstrates that tailoring the coating microstructure through powder design represents an effective strategy to enhance the CMAS resistance of APS‐YSZ coatings.