Yttria‐stabilized zirconia (YSZ) has been for several decades the state of the art material for thermal barrier coating (TBC) applications in gas turbines. Although the material has unique properties, further efficiency improvement by increasing the temperature is limited due to its maximum temperature capability of about 1200°C. Above this temperature the deposited metastable tetragonal (t´) phase undergoes a detrimental phase transformation as well as enhanced sintering. Both processes promote the failure of the coatings at elevated temperatures and this early failure has been frequently observed in gradient tests. In this paper, we now experimentally shown for the first time that under typical cycling conditions not the time at elevated temperatures leads to the reduced lifetime but the transient cooling rates. If cooling rates were reduced to 10K/s, TBC systems could be operated in a burner rig at a surface temperature well above 1500°C without showing a lifetime reduction. The explanation of these astonishing findings is given by the evaluation of energy release rate peaks during fast transient cooling in combination with the phase evolution during cooling with the used cooling rates.

Submicron Ti ₂ AlC MAX phase powder was synthesized by molten salt shielded synthesis (MS ³ ) using a Ti:Al:C molar ratio of 2:1:0.9 at a process temperature of 1000°C for 5 hours. The synthesized powder presented a mean particle size of ~0.9 µm and a purity of 91 wt. % Ti ₂ AlC, containing 6 wt. % Ti ₃ AlC ₂ . The Ti ₂ AlC powder was sintered by pressureless sintering, achieving a maximal relative density of 90%, hence field‐assisted sintering technology/spark plasma sintering was used to enhance densification. The fine‐grained microstructure was preserved, and phase purity of Ti ₂ AlC was unaltered in the latter case, with a relative density of 98.5%. Oxidation was performed at 1200°C for 50 hours in static air of dense monolithic Ti ₂ AlC with different surface finish, (polished, ground and sandblasted) which resulted in the formation of an approx. 8 µm thin aluminum oxide (Al ₂ O ₃ ) layer decorated with titanium dioxide (rutile, TiO ₂ ) colonies. Surface quality had no influence on Al ₂ O ₃ scale thickness, but the amount and size of TiO ₂ crystals increased with surface roughness. A phenomenon of rumpling of the thermally grown oxide (TGO) was observed and a model to estimate the extent of deformation is proposed.