Luminescence sensing of temperatures in thermal barrier coatings

One approach to measuring temperature in oxide coatings is to incorporate, within the crystal structure of the coating material itself, ions (“chromophores”) with temperature-dependent luminescence properties. The attraction of this “crystal chemistry” approach is that the other properties of the coating material, with appropriate choice of chromophore, are unaffected by solid solution doping. The method of luminescence sensing of temperature in both EB-PVD and plasma-sprayed coatings is described as well as the identification of the chromophores for the highest temperature measurements, the optimum doping concentrations and the excitation conditions. In addition, practical aspects in making precise temperature measurements will be presented.