Suppressing the phase-transition-induced cracking of SiO2 TGOs by lattice solid solution

The Si coating lifetime at 1350 degrees C is limited by the phase-transition-induced cracking of the SiO2 scale. In this study, Si-stabilizer duplex coatings were proposed to eliminate the unexpected phase transition. The results show that the diffusion of Al from the stabilizer to the SiO2 scale makes the high-temperature beta-SiO2 retain meta-stability to room temperature, thus avoiding phase-transition-induced cracking. Compared with the service lifetime of the pure Si coating, the lifetime of the duplex coating at 1350 degrees C is increased by more than 4 times. This research points to a way to design Si coatings with improved service lifetimes.