A computational modeling framework for reaction and failure of environmental barrier coatings under silicate deposits

William D. Summers, David L. Poerschke, Matthew R. Begley, Carlos G. Levi, Frank W. Zok

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

Environmental barrier coatings (EBCs) for use with SiC-based composites in gas turbine engines may fail following reaction with molten silicate deposits. The processes involved may include dissolution of the EBC material into the deposit, reactions that produce new phases, and cracking or spallation upon cooling, the latter driven by thermal expansion mismatch between the reaction products and the underlying EBC and substrate. Here, we describe an integrated computational framework to simulate the processes and to predict the conditions leading to coating loss through reactive consumption and/or spallation. The framework integrates distinct models to determine: (a) the nature and quantity of phases resulting from dissolution and chemical reactions; (b) thermo-physical properties of those phases; and (c) energy release rates for penetration cracking and spallation upon cooling. We demonstrate the use of the framework by computing critical deposit thicknesses for one specific EBC material (Y2Si2O7) as a function of deposit composition. In this system, the critical deposit thickness for typical coating thicknesses is dictated mainly by spallation, not by consumption, and may vary by orders of magnitude, depending on deposit composition and coating thickness and toughness. With respect to deposit composition, the key parameter governing coating failure is the Ca:Si ratio.

Original languageEnglish (US)
Pages (from-to)5196-5213
Number of pages18
JournalJournal of the American Ceramic Society
Volume103
Issue number9
DOIs
StatePublished - Sep 1 2020

Bibliographical note

Funding Information:
Research supported by the Pratt & Whitney Center of Excellence in Composites at the University of California, Santa Barbara. DLP gratefully acknowledges support through ONR grants N00014‐16‐1‐2702 and N00014‐17‐C‐2034, monitored by Dr D. Shifler.

Publisher Copyright:
© 2020 The American Ceramic Society

Copyright:
Copyright 2020 Elsevier B.V., All rights reserved.

Keywords

  • CMAS
  • ICME
  • Yttrium Disilicate
  • environmental barrier coating

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