SiC Substrate Composition Effect on TGO Scale Growth in EBC Systems During High-Temperature Steam Exposure

Kristyn D. Ardrey; Michael J. Lance; Mackenzie J. Ridley

doi:10.1111/jace.70540

SiC Substrate Composition Effect on TGO Scale Growth in EBC Systems During High-Temperature Steam Exposure

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Abstract

A systematic investigation was conducted on the oxidation behavior of silicon-bond coats within environmental barrier coating (EBC) systems applied to Si-carbide (SiC) substrates, aiming to understand how different underlying SiC substrates influence the bond coat's thermally grown oxide (TGO) and its properties. The study examined (Y/Yb)₂Si₂O₇/Si coatings on three cost-effective surrogate SiC substrates (chemical vapor deposition [CVD]-grown β-SiC, sintered α-SiC, and reaction-bonded [RB] SiC) for SiC_fiber/SiC_matrix ceramic matrix composites (CMCs). Discrepancies in TGO growth were observed, with noticeably higher growth rates reported for the coated CMC specimens than for the four monolithic SiC specimens. The CMC samples produce an amorphous TGO, whereas the other monolithic substrates formed a crystalline TGO, which lowered the oxygen permeability through the SiO₂ scale. The vitrification of the TGO in the (Y/Yb)₂Si₂O₇/Si/CMC system resulted from the migration of boron species from the CMC substrate to the SiO₂ scale, leading to network modification via boron doping.

Original language	English
Article number	e70540
Journal	Journal of the American Ceramic Society
Volume	109
Issue number	2
DOIs	https://doi.org/10.1111/jace.70540
State	Published - Feb 2026

Funding

This project was funded by the U.S. Department of Energy (DOE), Hydrocarbons and Geothermal Energy Office, project FEAA300 under contract DE-AC05-00OR22725 with Oak Ridge National Laboratory (ORNL) managed by UT Battelle LLC. Special thanks to Bryan Harder at NASA Glenn for providing CMC specimens; S. Sampath and E. Garcia-Granados from Stony Brook University for applying the EBC layer; Dr. Bruce Pint (retired, ORNL) for his advice and conceptual input; Jim Horenburg (ORNL's Metallography Division) for mounting, cross-sectioning, and polishing the specimens; George Garner and Michael Alexander for conducting cyclic furnace experiments; and Trevor G. Aguirre and Edgar Lara-Curzio for their technical reviews at ORNL. Access to the Raman spectrometer was provided by the Nuclear Nonproliferation Division, Oak Ridge National Laboratory. This manuscript has been authored by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (http://energy.gov/downloads/doe-public-access-plan). This project was funded by the U.S. Department of Energy (DOE), Hydrocarbons and Geothermal Energy Office, project FEAA300 under contract DE‐AC05‐00OR22725 with Oak Ridge National Laboratory (ORNL) managed by UT Battelle LLC.

Keywords

EBC
SiC
TGO
high-temperature oxidation
rare-earth

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10.1111/jace.70540

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title = "SiC Substrate Composition Effect on TGO Scale Growth in EBC Systems During High-Temperature Steam Exposure",

abstract = "A systematic investigation was conducted on the oxidation behavior of silicon-bond coats within environmental barrier coating (EBC) systems applied to Si-carbide (SiC) substrates, aiming to understand how different underlying SiC substrates influence the bond coat's thermally grown oxide (TGO) and its properties. The study examined (Y/Yb)2Si2O7/Si coatings on three cost-effective surrogate SiC substrates (chemical vapor deposition [CVD]-grown β-SiC, sintered α-SiC, and reaction-bonded [RB] SiC) for SiCfiber/SiCmatrix ceramic matrix composites (CMCs). Discrepancies in TGO growth were observed, with noticeably higher growth rates reported for the coated CMC specimens than for the four monolithic SiC specimens. The CMC samples produce an amorphous TGO, whereas the other monolithic substrates formed a crystalline TGO, which lowered the oxygen permeability through the SiO2 scale. The vitrification of the TGO in the (Y/Yb)2Si2O7/Si/CMC system resulted from the migration of boron species from the CMC substrate to the SiO2 scale, leading to network modification via boron doping.",

keywords = "EBC, SiC, TGO, high-temperature oxidation, rare-earth",

author = "Ardrey, \{Kristyn D.\} and Lance, \{Michael J.\} and Ridley, \{Mackenzie J.\}",

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AU - Ardrey, Kristyn D.

AU - Lance, Michael J.

AU - Ridley, Mackenzie J.

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N2 - A systematic investigation was conducted on the oxidation behavior of silicon-bond coats within environmental barrier coating (EBC) systems applied to Si-carbide (SiC) substrates, aiming to understand how different underlying SiC substrates influence the bond coat's thermally grown oxide (TGO) and its properties. The study examined (Y/Yb)2Si2O7/Si coatings on three cost-effective surrogate SiC substrates (chemical vapor deposition [CVD]-grown β-SiC, sintered α-SiC, and reaction-bonded [RB] SiC) for SiCfiber/SiCmatrix ceramic matrix composites (CMCs). Discrepancies in TGO growth were observed, with noticeably higher growth rates reported for the coated CMC specimens than for the four monolithic SiC specimens. The CMC samples produce an amorphous TGO, whereas the other monolithic substrates formed a crystalline TGO, which lowered the oxygen permeability through the SiO2 scale. The vitrification of the TGO in the (Y/Yb)2Si2O7/Si/CMC system resulted from the migration of boron species from the CMC substrate to the SiO2 scale, leading to network modification via boron doping.

AB - A systematic investigation was conducted on the oxidation behavior of silicon-bond coats within environmental barrier coating (EBC) systems applied to Si-carbide (SiC) substrates, aiming to understand how different underlying SiC substrates influence the bond coat's thermally grown oxide (TGO) and its properties. The study examined (Y/Yb)2Si2O7/Si coatings on three cost-effective surrogate SiC substrates (chemical vapor deposition [CVD]-grown β-SiC, sintered α-SiC, and reaction-bonded [RB] SiC) for SiCfiber/SiCmatrix ceramic matrix composites (CMCs). Discrepancies in TGO growth were observed, with noticeably higher growth rates reported for the coated CMC specimens than for the four monolithic SiC specimens. The CMC samples produce an amorphous TGO, whereas the other monolithic substrates formed a crystalline TGO, which lowered the oxygen permeability through the SiO2 scale. The vitrification of the TGO in the (Y/Yb)2Si2O7/Si/CMC system resulted from the migration of boron species from the CMC substrate to the SiO2 scale, leading to network modification via boron doping.

KW - EBC

KW - SiC

KW - TGO

KW - high-temperature oxidation

KW - rare-earth

UR - https://www.scopus.com/pages/publications/105029037325

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DO - 10.1111/jace.70540

M3 - Article

AN - SCOPUS:105029037325

SN - 0002-7820

VL - 109

JO - Journal of the American Ceramic Society

JF - Journal of the American Ceramic Society

IS - 2

M1 - e70540

ER -

SiC Substrate Composition Effect on TGO Scale Growth in EBC Systems During High-Temperature Steam Exposure

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