Measurement of advanced ceramic coated superalloys with a long wavelength pyrometer

Depth-penetrating temperature measurements of thermal barrier coatings incorporating thermographic phosphors

“…One successful approach has been to develop long-wavelength (>10 µm) pyrometers that operate at wavelengths where the TBCs are opaque (to allow surface measurements) and the TBCs exhibit near-zero reflectance (to minimize interference of reflected radiation), but with the drawback of much lower signal and sensitivity than at shorter wavelengths. [3,4] Another successful approach has been to apply thermographic phosphors to the TBC surface to obtain emissivity-independent surface temperature measurements either by the temperature dependence of the fluorescence decay time or by the ratio of intensities of selected emission lines. [5,6] One aspect of the potential for using thermographic phosphors for TBC temperature measurements that has not been well explored is to take advantage of the TBC translucency to place the phosphor not only at the surface, but at any depth where the temperature measurement is desired.…”