On the thermal sensitivity and resolution of a YSZ:Er 3+ /YSZ:Eu 3+ fluorescent thermal history sensor

Abstract This paper deals with the problem of thermal history analysis of high temperature components for applications such as furnaces, nuclear reactors and jet engines. It focuses on fluorescent thermal history sensors, which exhibit permanent changes in their luminescence properties when exposed to high temperature. These changes can then be quantitatively evaluated to determine the temperature of exposure from a previous thermal event. The main objective of this paper is to investigate the thermal sensitivity and the thermal resolution of a yttria-stabilized zirconia (YSZ) Er 3+ -doped phosphor produced by a sol-gel route and combined with a thermal history insensitive YSZ:Eu 3+ reference, which was selected for its high sensitivity to thermal history above 1173 K. In particular, the interest of this YSZ:Er 3+ /YSZ:Eu 3+ sensor is discussed in the view of the physical properties of sol-gel deposited YSZ coatings, the selection of an appropriate excitation wavelength and the practical measurement of coatings fluorescence properties. The sensitivity and the resolution of two thermal history measurement fluorescence methods, based on intensity ratios and lifetime analysis, were determined and compared. A comparison is also made with standard non-contact temperature measurement methods such as infrared thermography and thermochromic paints.