Environmental Barrier Coating Surface Temperature Mapping Using a Compatible Er-Doped Sc2SiO5 Temperature-Sensing Layer

Accurate surface temperature-mapping capabilities in the 1300 to 1500 °C range are needed for SiC/SiC ceramic matrix composites protected by environmental barrier coatings (EBCs) under testing in turbine engine environment facilities. The strong background thermal radiation at these higher temperatures is a challenging issue. Er-doped Y2SiO5 was previously shown to be capable of achieving luminescence lifetime-based temperature mapping up to 1560 °C as a standalone material. However, compatibility issues between an Er-doped Y2SiO5 surface temperature sensing layer and an underlying Sc2Si2O7-based EBC topcoat limited temperature mapping of the EBC surface to a maximum of 1380 °C. Therefore, an Er-doped Sc2SiO5 temperature sensing layer has been subsequently developed with better compatibility with the Sc2Si2O7-based EBC topcoat. Localized spot temperature measurements as well as luminescence lifetime imaging-based temperature mapping were demonstrated up to 1535 °C from a 15 µm thick Er-doped Sc2SiO5 layer at the surface of a Sc2Si2O7-based EBC topcoat, a significant improvement over the Er-doped Y2SiO5 layer 1380 °C temperature sensing limit. No degradation of the Er-doped Sc2SiO5 temperature sensing surface layer was observed.