Experimental Investigation on High-Temperature Fatigue and Fracture Properties at the Interface Between Thermal Barrier Coatings (Tbcs) and Nickel Based Superalloy Substrate
热障涂层-基体体系界面高温疲劳和断裂性能的实验研究

Employed as thermal protection coating for engine blades, thermal barrier coatings (TBCs) can significantly increase service life of these components in a high-temperature environment. A systematic investigation on the properties of interface between TBCs and nickel based superalloy substrate was carried out. The elasticity modulus of ceramic layer, the hardness of ceramic coat and the microstructure change near the ceramic layer - adhesive layer interface before and after isothermal heat treatment were experimentally obtained and compared. Results show that during isothermal heat treatment, the ceramic coat sintering has occurred but there is not phase transformation; besides, both Young's modulus and the hardness increase first then decrease along with the heat treatment time increasing; the thickness of oxide layer grows along with the heat treatment time and temperature increasing. Moreover, by using multi-phase angle interfacial fracture toughness test method proposed in this paper, a failure criterion for TBCs interface was established in terms of stress intensity factors as characterization parameters. Assuming the interfaces is viscous contact, the evolution of interface carrying capacity along with the increasing of ceramic coat Young's modulus and oxide layer thickness was predicted. Thermal fatigue properties and failure mechanism of interface between TBCs and nickel based superalloy substrate were investigated by thermal cycling test. Results reveal that along with the increase of thermal cycle temperature holding time, the fatigue life increases first then decreases, and the failure mode translates from single interface failure into both interface failure and ceramic failure.