Failure mechanism of thermal barrier coatings of an ex-service aero-engine combustor

Failure mechanism analysis of thermal barrier coatings (TBCs) on an ex-service aero-engine combustor is carried out. Microstructure, chemical composition, phase composition, and Youngs modulus of TBCs are detected for three typical spallation areas as well as an as-sprayed sample for reference. A fluid-structure interaction simulation for the turbulent combustion is conducted to obtain the working temperature, fuel impurities mass fraction and dust particles erosion rate distribution on the TBCs surface. Results show that the maximum working temperature, the impurity mass fraction, and the sucked-in dust erosion rate correspond to the spallation at the outer liner complementary combustion zone (CCZ), the outer liner primary combustion zone (PCZ), and the inner liner of CCZ respectively. It is found the failure of TBCs at outer liner of CCZ is caused by high-temperature sintering, the infiltration of deposits is the main reason for the failure of TBCs at outer liner of PCZ, and the combination of sintering and particles impact is responsible for the failure of TBCs at inner liner of CCZ. Besides, the accumulation of inelastic strain in the vicinity of thermally growth oxide (TGO) caused by thermal stress may lead to formation and propagation of cohesive interfacial cracks.