Properties Evaluation of a Novel Entropy-Stabilized Ceramic (La0.25Ce0.25Nd0.25Sm0.25)Ti2Al9O19 with Enhanced CMAS Corrosion Resistance for Thermal Barrier Coating Applications

In this work, a novel potential thermal barrier coating material entropy-stabilized titanium-aluminum oxide (La_0.25Ce_0.25Nd_0.25Sm_0.25)Ti₂Al₉O₁₉ (META) was successfully synthesized by the solid-state reaction method, and its thermophysical properties, phase stability, infrared emissivity, mechanical properties, and CMAS corrosion resistance were systematically investigated. The results demonstrated that META exhibits low thermal conductivity at 1100 °C (1.84 W·(m·K)^-1), with a thermal expansion coefficient (10.50 × 10^-6 K^-1, 1000-1100 °C) comparable to yttria-stabilized zirconia (YSZ). Furthermore, META displayed desirable thermal stability, high emissivity within the wavelength range of 2.5-10 μm, and improved mechanical properties. Finally, META offers superior corrosion resistance due to its excellent infiltration inhibiting. The bi-layer structure on the corrosion surface prevents the penetration of the molten CMAS. Additionally, doping small-radius rare-earth elements thermodynamically stabilizes the reaction layer. The results of this study indicate that (La_0.25Ce_0.25Nd_0.25Sm_0.25)Ti₂Al₉O₁₉ has the potential to be a promising candidate for thermal barrier coating materials.