Sintering governing the cracking behaviors of different La2Zr2O7/YSZ ceramic layer combination TBCs at 1150 °C

Abstract Sintering behavior is one of the most important indicators correlated to the service behaviors for thermal barrier coatings (TBCs). 5 different La2Zr2O7(LZO)/YSZ double ceramic layer (DCL) combination TBCs are subjected to gradient thermal cyclic tests under the surface temperature of 1150 °C, aiming to elucidate the service behaviors of the DCL TBCs under relative low temperature. The failure of DCL TBCs is the cracking of top coat along in-plane direction, the 8YSZ TBCs showed an vertical cracking after 2200 cycles, and the stress state transferred from tensile about 250 MPa to compressive of −60 MPa. The pure 8YSZ is superior to the DCL TBCs for the long-term application at relative low temperature. Sintering induced the competition of cracking driving force and resistance dominates the cracking of TBCs, the formation of vertical cracks released the stress of the 8Y TBCs system to a large extent and the lifetime was extended.