Comparison of IR thermography and photoluminescence for early diagnostic of spallation and temperature sensing in thermal barrier coatings
Résumé
Spallation of Thermal Barrier Coatings (TBCs) in gas turbines is the result of the insidious initiation and propagation of microcracks at the interface with the substrate. This temperature driven mechanism is difficult to detect in its early stage and the difficulty of determining accurately the interface temperature hinders the development of reliable lifetime prediction models. In this work, two non destructive diagnostic methods based on IR thermography and photoluminescence are compared for early damaging assessment of TBCs prepared by a sol-gel route containing pre-calibrated delaminated areas and integrating a Eu3+ doped photoluminescent layer at the interface with the substrate. The potential of the later method for through-thickness temperature sensing is also discussed.