Yb₂SiO₅-Yb₂Si₂O₇ gradient environment barrier coating: Rational design and corrosion behavior in water vapor environment at 1300 ℃

Gradient environmental barrier coatings (EBCs) were fabricated via atmospheric plasma spraying to deposit Yb₂Si₂O₇-Yb₂SiO₅ onto a laser-sculpted SiC substrate, with varying mass ratios. Experimental results reveal that the gradient coating exhibited remarkable integrity, showing no signs of cracking even after exposure to 90% H₂O-10% O₂ (g) water vapor corrosion at 1300 ℃ for 100 h. Besides, the thickness of the thermally grown oxide (TGO) layer was minimal (18.53 ± 1.08 μm) compared to 75Yb₂Si₂O₇-25Yb₂SiO₅ single layer EBCs (24.93 ± 1.62 μm) with similar integrity under water vapor environment for 100 h. The superior performance of the gradient coating against water vapor corrosion can be attributed to the outmost layer containing more Yb₂SiO₅ with excellent vapor corrosion resistance, while the innermost layer primarily comprises Yb₂Si₂O₇, providing significant damage resistance and resilience to thermal shock. These favorable attributes make the gradient coating a promising candidate for EBC application in aerospace.