Corrosion behaviors and failure mechanism of plasma sprayed Yb2Si2O7/Si environmental barrier coatings exposed to CMAS+ NaVO3

Aero-engine service environments are complex and variable, environmental barrier coatings are usually exposed to the coupled corrosion of CMAS and molten salt. Clarifying the relevant corrosion mechanisms is of guiding significance for the protection of environmental barrier coatings. In this study, the CMAS+NaVO₃ (CN) corrosion behavior of a typical Yb₂Si₂O₇/Si coating prepared by atmospheric plasma spray (APS) technique was explored. Results showed that CN was completely melted and uniformly spread at 1200℃, a temperature lower than the melting point of CMAS. Interaction between the Yb₂Si₂O₇/Si coating and CN produced a discontinuous non-stoichiometric garnet phase at 1200℃. At 1300 °C, the reaction produced an apatite reaction layer, but when the duration was extended to 50 h, the apatite layer was gradually dissolved. Moreover, the CN melt infiltrated into the entire Yb₂Si₂O₇ coating, causing buckling of the Yb₂Si₂O₇ layer and debonding with the Si layer, ultimately leading to failure of the Yb₂Si₂O₇/Si coating.