Research Progress On High-Entropy Ceramics For Thermal Barrier Coatings Materials: From Material Design to Property Optimization

Thermal barrier coatings (TBCs) enable high-temperature service for hot-section components. However, conventional 6–8 wt% yttria-stabilized zirconia (YSZ) suffers from phase decomposition, sintering, and CaO-MgO-AlO 1.5 -SiO 2 (CMAS) attack above 1200 °C, thereby limiting its application. High-entropy ceramics (HECs) offer a promising design paradigm through multiprincipal element solid solutions and their associated four core effects, enabling ultra-low thermal conductivity, enhanced toughness, tunable thermal expansion coefficients (TECs), high-temperature phase stability, and improved CMAS resistance. This review first establishes the thermodynamic and kinetic foundations of HECs, and then systematically surveys the major HECs systems developed for TBCs, including fluorite, pyrochlore, perovskite and ABO4 HECs, with emphasis on their crystal structures and corresponding property characteristics. Key property optimizations, encompassing thermal conductivity, toughening mechanisms, TECs, phase stability, and corrosion resistance, are critically analyzed, and the inherent composition–structure–property interrelationships are elucidated. This review aims to provide a comprehensive theoretical framework and practical guidance for the rational design and engineering application of HECs as top-coat (TC) materials for TBCs.