Computational Tool To Accelerate Design Of CMAS-Resistant Thermal And Environmental Barrier Coatings For Aero-Turbine Applications

Infiltration of molten Calcium-Magnesium Alumino-Silicate (CMAS), the main constituents of sand, ash, soot, and other environmental deposits ingested into aero-turbine engines during flight, is a primary cause of failure of thermal barrier coatings (TBCs) used on turbine blades. Additionally, CMAS reactions with fully-dense environmental barrier coatings (EBC) of interest for next-generation ceramic matrix composite (CMC)-based turbine materials can result in coating recession, also leading to coating failure. The thermodynamic properties of the CMAS melt (viscosity, melting point, etc.) and the crystalline reaction products formed due to the interaction between the CMAS melt and coating material, have a major impact on infiltration/recession kinetics and resulting coating lifetime. Additional complexity of CMAS/coating interaction is added due to the wide range of CMAS deposit compositions found in nature, which can lead to vastly disparate melt behavior and CMAS-TBC reactivity dependent on both deposit and coating composition. A computational design tool has been developed to enable predictive modeling of CMAS-T/EBC interaction and coating performance. This computational tool leverages CALPHAD (Computer Coupling of Phase Diagrams and Thermochemistry) thermodynamic databases which include the components of CMAS-Fe deposits as well as RE zirconates (RE=Y,Gd) and other oxides of interest for coatings. The tool enables TBC design by streamlining thermodynamic calculations related to CMAS melt properties and CMAS/TBC reactivity, allowing for fast and efficient assessment across a wide range of customizable deposit and coating compositions. Examples of tool functionalities and relevant thermodynamic calculations will be presented.