Corrosion of Yb2SiO5/Yb2Si2O7/Si EBCs against Na2SO4 + 25 wt%NaCl molten salt at 1350 ℃

Abstract

The reaction behaviors and corrosion mechanisms of tri-layer Yb2SiO5/Yb2Si2O7/Si EBCs were explored in Na2SO4 + 25 wt%NaCl molten salt environment at 1350 °C. Results showed that the molten salt rapidly penetrated the Yb2SiO5 layer and then reacted with the Yb2Si2O7 layer to form SiO2-riched Na-Yb-Si-O glass phase. The reaction product of glass phase diffused to the EBCs surface through the cracks and reacted with Yb2SiO5 to form Yb2Si2O7. The reaction of Yb2Si2O7 caused the development of transverse cracks, which eventually led to the failure of the EBCs. Moreover, the Yb2SiO5 layer exhibited better corrosion resistance than the Yb2Si2O7 layer.