Preparation and thermo-physical properties of La₂AlTaO₇ ceramic for thermal barrier coating application

In this work, La2AlTaO7 (LAT) ceramic was fabricated with the solid-state reaction method. The high temperature stability, mechanical properties and thermo-physical properties of LAT ceramic were studied. The thermal cycling lifetime of LAT thermal barrier coating (TBC) was also evaluated. Results showed that thermal conductivity of LAT ceramic was lower than that of 8% Y2O3-stabilized zirconia (YSZ) and decreased with the increase of the temperature, from 2.01 W/(m*K) at room temperature to 1.85 W/(m*K) at 1000 ?C. The thermal expansion coefficient (TEC) of LATceramic was comparable to that of YSZ. The LAT ceramic also exhibited excellent thermal stability from room temperature to 1250 ?C. The premature failure of the LAT TBCs during the thermal cycling test can be mainly attributed to the low fracture toughness, thermal expansion mismatch and high sintering rate.