Prolong the durability of La₂Zr₂O₇/YSZ TBCs by decreasing the cracking driving force in ceramic coatings

Service lifetime and thermal insulation performance are both crucial for the application of thermal barrier coatings (TBCs). In this study, layered structure design under equivalent thermal insulation conception is introduced to lower the cracking driving force in TBCs, and with the goal of prolonging TBCs lifetime. Three groups of layered LZO/YSZ TBCs were designed with same thermal insulation of 500 μm YSZ, the LZO layers were deliberately designed with different initial elastic modulus. Virtual crack closure technique (VCCT) calculation result showed that the energy release rates at the crack tips are 28.2, 22, and 18.8 N/m corresponding to the initial elastic modulus of 70, 60, and 50 GPa. After gradient thermal cyclic tests with surface temperature of 1300 °C, TBCs with lowest initial elastic modulus showed the longest lifetime, and more than double of pure YSZ TBCs. This study provides a new option for the improvement of TBCs lifetime.