Process-Property-Performance Relationships of YSZ and GDZ Air Plasma Sprayed Thermal Barrier Systems Regarding CMAS Attack

Increased gas turbine operating temperatures have concurrently ushered in the need for innovation and development in thermal barrier (TBC) materials and their processing. As the operating temperatures in natural gas-fired combine cycle (NGCC) and integrated gasification combined cycle (IGCC) plants increases, the possibility for ingested siliceous debris (CMAS) to pose a threat to the ceramic topcoat on the metallic components of the engine increases; this is particularly true in engines employing the use of syngas in their operation. These CMAS particles typically have melting temperatures near the newly increased gas operating temperatures, and as such, can be molten or semi-molten upon ingestion and effectively “wick” into the interconnected porosity of plasma sprayed TBCs. Results indicate a correlation between processing parameters, microstructure, and resistance to CMAS attack for both single and multilayer, YSZ/GDZ combination TBCs. Additionally, coatings which have engineered segmented microstructures (DVC) also have independent interaction mechanisms with molten silicates.