Application of phase equilibrium modeling to understand and mitigate the CMAS threat in thermal and environmental barrier coatings

Conference Dates

June 24-29, 2018


The severity of thermal and environmental barrier coating (T/EBCs) degradation caused by molten silicate deposits (CMAS) is directly influenced by (i) the composition of the deposit, (ii) the component surface temperature and through-thickness gradient, and (iii) the composition of the coating material. Given the breadth of this parameter space, assessing the performance of even a single candidate coating material against all possible deposit compositions and thermal conditions is experimentally intractable. Instead, it is more efficient to develop computational thermodynamics models in order to select relevant conditions for testing and, ultimately, to guide the identification and selection of coating materials/architectures offering improved performance.

This presentation will describe efforts to develop robust thermodynamic models of the higher-order composition space (7+ components) relevant to the design of rare earth (RE)-containing T/EBCs. These efforts involve studying the detailed phase equilibria and crystal chemistry in key subsystems, validation of thermodynamic databases through targeted experiments in higher-order systems, and the development of modeling tools to predict compositional trends and reaction sequences.

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