<p>Environmental barrier coatings (EBCs) for Si-based ceramic matrix composites (CMCs) play an increasingly important role in next-generation gas turbine engines. A high-performance and highly durable EBC system depends on the material composition, coating process, and coating architecture. In this study, four thermal environmental barrier coating (TEBC) systems based on Yb₂SiO₅/Yb₂Si₂O₇/Si and Gd₂Zr₂O₇/Yb₂Si₂O₇/Si chemistries were designed and developed using the plasma spray process. Calcium–magnesium–alumina–silicate (CMAS) corrosion tests on the multilayer TEBCs were investigated. Furthermore, high-temperature coating durability was evaluated and tested in a steam cycling environment. The relationships among phase composition, microstructure, coating process, and properties were discussed. The CMAS and steam cycling test results demonstrated that LPPS Yb₂SiO₅/Yb₂Si₂O₇/Si TEBC is a promising coating solution for a highly durable TEBC for the protection of CMC components in water vapor and CMAS environments.</p>