Thermal shock resistance of TiAlCrY/rare-earth aluminate ceramics thermal barrier coatings on TiAl single crystals

Abstract

TiAl single crystals have received much attention in aviation industry owing to their low density and excellent high-temperature properties. Yet, their poor oxidation resistance above 1000 °C limits their widespread applications. Rare-earth aluminate ceramics such as LaMgAl₁₁O₁₉ (LaMA) and Y₃Al₅O₁₂ (YAG) are promising thermal barrier coating (TBC) candidates because of their high thermal stability and low oxygen permeability. In this study, LaMA and YAG powders were synthesized and deposited as top coats on TiAlCrY bond-coated TiAl substrates via APS. Their thermophysical properties and thermal shock resistance at 1100 °C were systematically explored. Results showed that both LaMA and YAG coatings exhibited superior oxygen barrier performance compared to conventional YSZ, mainly due to their lower oxygen vacancy concentrations. Besides, the LaMA/TiAlCrY TBC achieved a thermal shock lifetime of about 150 cycles, three times that of the YAG-based system, and comparable to YSZ/MCrAlY TBCs on Ni-based superalloys. The improved durability of the LaMA coating was attributed to better CTE compatibility, reduced amorphous phase crystallization, and lower elastic modulus, which together mitigated thermal stress-induced cracking. These results provide insights into the design of high-performance TBCs for TiAl-based components.