Thermal Radiative Properties and Temperature Measurement from Turbine Coatings

Recent studies have displayed the spectral radiative properties of ceramic thermal barrier coatings which are finding applications in high performance turbine engines. As a function of temperature, a region in the long wavelength infrared spectrum exhibits properties which will minimize the classical errors associated with temperature measurement by radiometric detection. Hollow sapphire waveguides transmit the portion of the long wavelength infrared spectrum which is optimum for radiometric temperature measurement from these materials, while the physical properties of the sapphire can withstand the combustion conditions within the engine. A prototype long wavelength infrared radiation thermometer was constructed to obtain surface temperature measurements from coated turbine blades subjected to high temperature combustion conditions.