Microstructural and Mechanical Investigation of CYSZ/MCrAlY Thermal Barrier Coatings: A Comparison of APS and SPS Processes

This study investigates the microstructure and mechanical properties of Ceria-Yttria-Stabilized Zirconia (CYSZ) thermal barrier coatings (TBCs) with a NiCoCrAlY bond coat, fabricated using Atmospheric Plasma Spraying (APS) and Spark Plasma Sintering (SPS). TBCs play a vital role in high-temperature applications within the aerospace and automotive industries. APS coatings demonstrated greater porosity, increased thermally grown oxide (TGO) formation, and more significant thermal degradation at elevated temperatures. Conversely, SPS coatings were denser with superior adhesion, lower porosity, and enhanced mechanical properties, including higher microhardness. Phase analysis showed APS reduced CeO₂ content and transformed zirconia phases, while SPS preserved the original phase composition, ensuring better structural integrity and thermal stability. Overall, SPS outperformed APS in mechanical strength, phase stability, and oxidation resistance, making it a superior method for producing high-performance TBCs.