Failure and Damage Evaluation of Thermal Barrier Coatings under Extreme Environments

Failure and damage of thermal barrier coatings (TBCs) are preliminary phenomena significantly affecting their applications in gas turbine engines. Cracking and delamination of TBCs typically occur due to thermal mismatch stresses resulting in coating spallation and failure. Multiple-factors, such as coating layers creep, topcoat sintering, oxidation of bond coat and interface imperfection, are coupled to lead to TBCs failure. This presentation shows the failure and damage of TBCs under extreme environments evaluated using multi-physics modelling. Heat transfer was implemented into TBC model to simulate in-service cyclic operation conditions. Phase-field damage modelling was conducted to demonstrate fracture-damage evolution of TBCs topcoat. Coating interface degradation was investigated using the cohesive zone model. Results show that topcoat cracks propagate rapidly during an early stage and then continue to grow as the topcoat is sintered. Using the cohesive zone model, more crack paths are studied, and the predominated effect on crack growth was identified.