Design Principles of Composite Oxides for High‐Temperature Thermal and Environmental Barrier Coatings: A Review

ABSTRACT The increasing performance demands of aerospace engines and heavy‐duty gas turbines require materials capable of withstanding extreme thermal environments. Ceramic matrix composites protected by environmental barrier coatings are promising materials for hot‐section components. As operating temperatures continue to rise, the integration of thermal barrier coatings on top of the environmental barrier coatings has become essential to further enhance thermal protection, forming a thermal and environmental barrier coating (TEBC) system. Despite extensive research efforts, no single ceramic material currently meets the stringent requirements of TEBC systems. Consequently, composite oxide coatings have emerged as a promising strategy to synergistically optimize thermophysical and mechanical properties. This review critically analyzes recent advances in composite oxides for TEBC systems, focusing on their thermo‐mechanical performance, environmental durability, failure mechanisms, and design principles. Overall, this review provides insights for the rational design of next‐generation TEBC systems.