Abstract
The aim of this study is to evaluate the thermal lifetime properties of yttria-stabilized zirconia (YSZ) coatings with a columnar microstructure. YSZ suspensions were sprayed under different conditions in order to obtain a sample lot with columnar microstructures varying from well-separated to closely spaced. Thermo-cyclic fatigue (TCF) tests were performed at 1100 °C and the results are presented. Coatings with well-separated columns reached 2150 cycles prior to failure compared to 1300 cycles in the case of coatings with compact columns. The apparent lower TCF resistance is attributed to a loss of thermal compliance inducing the development of sharp intercolumnar cracks. Failures seem to be linked to debonding at the TGO-substrate interface. The bond coat and substrate surface roughness also play a role in such failures and their impact is discussed.
