β‐Cristobalite thermal expansion and stability in environmental barrier coating systems

Abstract SiC‐based ceramic matrix composites (CMCs) for turbine engine applications require environmental barrier coatings (EBCs) to protect against water‐vapor induced corrosion. A significant limiting factor of EBC operating lifetime is the formation of a SiO 2 thermally grown oxide (TGO) at the EBC–CMC interface at high temperature. Its rapid growth as well as displacive β→α cristobalite phase transformation upon cooling induces strains at this interface, which can result in coating spallation. Recent work has explored upon the use of modifier oxides in EBCs to reduce oxidizing specie transport and possibly stabilize the SiO 2 TGO. This work utilizes EBC–glass mixtures to characterize the properties of modifier‐stabilized SiO 2 and assess its impact in future EBC systems.