Calibration of Laser Piezospectroscopy Using Alumina/Chromia Solid Solutions Obtained by Coprecipitation

Cr3+ photoluminescence peizo-spectroscopy (CPLPS) is a technique that allows the measurement of the hydrostatic component of stress in α alumina oxides. This method is being developed in our laboratory as a non-destructive inspection technique for thermal barrier coating systems. It has been shown that the Cr3+ concentration influences the magnitude of the shifts in the fluorescence frequencies, Δv of the R1 and the R2 peaks [1,2] and hence the apparent stress. Therefore, this work is an attempt to quantify the extent of this shift, consequent to the Cr3+ concentration in the TBC systems and to study the variation of this effect with thermal cycles on the TBCs. In addition, we have developed a method of estimating Cr3+ content based on the intensity of satellite peaks referred to as n-lines. The experiments are also designed to validate the n-line based method of estimating Cr3+ content and its affect on the apparent stress value.