Evaluating the service performance of Yb₂Si₂O₇ environmental barrier coatings on laser textured SiC surface at 1450°C

Common environmental barrier coatings (EBCs) are currently temperature-limited by the Si bond coat, whose melting temperature is ∼1414 °C. This work explored novel single layer Yb₂Si₂O₇ coating without Si bond coat to achieve higher operating temperatures. Different versions of texture were constructed on the SiC substrate surface via ultrafast laser direct writing technology to enhance the coating adhesion to the substrate. The thermal cycling lifetime of Yb₂Si₂O₇ coating deposited on the grit-blasted SiC surface (coating A) at 1450 °C is only 47 cycles, and that of coating deposited on the laser textured SiC surface has a distinct improvement. Especially, in the case of 50 μm laser scanning interval, the average lifetime reaches to 346 cycles. The existence of texture (including peak and valley) inhibits the propagation of cracks along the Yb₂Si₂O₇ layer/SiC interface to some extent, enhancing the mechanical adhesion. During the oxidation in a dry air environment at 1450 °C, coating A completely delaminates after 150 h, whereas other coatings still maintain a good interfacial adherence after 200 h. Meanwhile, both their TGO thickness and growth rate are lower than that of former due to the excellent protection of Yb₂Si₂O₇ layer. In the case of steam environment, the degradation of all coatings is more serious, characterized by the premature separation and Yb₂SiO₅ phase transformation. In addition, the synergistic effect of O₂ and H₂O oxidants contributes to the thicker TGO. These finds here are expected to provide valuable insights for the design of next-generation EBCs.