Evaluation of diffusion processes in Thermal Barrier Coatings to assess the life cycle
Evaluation of diffusion processes in Thermal Barrier Coatings to assess the life cycle
Tuesday, May 6, 2025
Exhibit Hall - East Hall AB (Vancouver Convention Centre)
Thermal Barrier Coatings (TBCs) can effectively protect the alloy substrate of hot components in gas-turbine engines by the thermal insulation and corrosion/erosion resistance of the ceramic top coat.
Ceramics provide thermal insulation to the super alloy parts thus introduces a temperature gradient enabling high combustion temperatures while avoiding high temperature degradation such as creep, oxidation, hot corrosion, erosion etc.
TBCs therefore, are considered as a complex material system constitutes not only of the oxide ceramic coating (top coat) itself, but also metallic bond coat layer that is more oxidation resistance than super alloy and a thin thermally grown oxide layer (TGO) that forms between the top coat and bond coat as a result of bond coat oxidation in service.
In this work, several types of TBCs were applied to a nickel superalloy having service exposure of 1000 hours.
The microstructural examinations were carried out using optical and scanning electron microscopy techniques.
Growth of TGO layer and inter-diffusion of species within the layers including the substrate have been identified as the parameters for estimating the exhausted life fraction of the degraded coatings.
Finally, it has been concluded that parameters like TGO layer growth, diffusion rate and distribution of elements have the potential to assess the life cycle evaluation of TBCs.
Ceramics provide thermal insulation to the super alloy parts thus introduces a temperature gradient enabling high combustion temperatures while avoiding high temperature degradation such as creep, oxidation, hot corrosion, erosion etc.
TBCs therefore, are considered as a complex material system constitutes not only of the oxide ceramic coating (top coat) itself, but also metallic bond coat layer that is more oxidation resistance than super alloy and a thin thermally grown oxide layer (TGO) that forms between the top coat and bond coat as a result of bond coat oxidation in service.
In this work, several types of TBCs were applied to a nickel superalloy having service exposure of 1000 hours.
The microstructural examinations were carried out using optical and scanning electron microscopy techniques.
Growth of TGO layer and inter-diffusion of species within the layers including the substrate have been identified as the parameters for estimating the exhausted life fraction of the degraded coatings.
Finally, it has been concluded that parameters like TGO layer growth, diffusion rate and distribution of elements have the potential to assess the life cycle evaluation of TBCs.