Promoting Yb₂Si₂O₇ environmental barrier coatings for service at 1425 °C

Si-based environmental barrier coatings (EBCs) are indispensable for SiC composites. However, the service temperature of next-generation composites exceeds 1400 °C, leading to melting of the Si bond coat. To mitigate this issue, Yb₂Si₂O₇ (YbDS) and mullite/YbDS coatings without Si bond coat were proposed. The results indicate that YbDS coatings can survive for 150 h at 1425 °C, while mullite/YbDS coatings experienced significant spallation during this period. Both SiO₂ phase transition and interfacial holes cause spallation of the YbDS and mullite/YbDS coatings. This research provides valuable insights for designing next-generation EBCs.