Sintering of electron beam physical vapor deposited thermal barrier coatings under flame shock

Flame shock treatment of electron beam physical vapor deposited (EB-PVD) thermal barrier coatings (TBCs) was carried out to investigate the degradation of TBCs exposed to a temperature gradient. The flame treatment resulted in temperature gradients both in the surface plane and through the thickness of the TBCs. TBC densification occurred where the flame was centered and resulted in a fine crack network at the surface of the TBC. The TBCs with addition of 0.5 wt% alumina were made, in which alumina was used as stress sensors for stress measurements by photoluminescence piezo-spectroscopy (PLPS). This allowed stress measurements to be made through the TBC thickness using a depth sensing method. Such stress measurements help us to better understand the densification of the TBCs.