Quantitative evaluation of (0001) sapphire recession in high-temperature high-velocity steamjet exposures

Mackenzie J. Ridley; Elizabeth J. Opila

doi:10.1016/j.jeurceramsoc.2021.07.064

Quantitative evaluation of (0001) sapphire recession in high-temperature high-velocity steamjet exposures

Mackenzie J. Ridley, Elizabeth J. Opila

Research output: Contribution to journal › Article › peer-review

2 Scopus citations

Abstract

High-temperature high-velocity steam exposures of (0001) sapphire coupons were performed at temperatures of 1200 °C–1450 °C to determine the quantitative capability of the steamjet apparatus. Recession results were compared to calculated values of Al(OH)₃ (g) mass transfer rates based on laminar flow models and available thermodynamic data for Al(OH)₃ (g). Linear material volatilization rates and a strong gas velocity dependence on the reaction depth confirmed that the Al₂O₃ reaction was controlled by a gas-phase diffusion process. The temperature dependence for the steam reaction agreed with thermodynamic calculations and with the literature, confirming that Al(OH)₃ (g) transport through a gas boundary layer represents the rate-limiting step for Al₂O₃ volatilization in steam. The steamjet experimental setup can thus be utilized for determination of steam-oxide reaction thermodynamics given known steam flow conditions. Steamjet test recession results for simple oxides are discussed for comparison with behavior of complex oxides that form porous product layers, which are not yet well understood.

Original language	English
Pages (from-to)	631-637
Number of pages	7
Journal	Journal of the European Ceramic Society
Volume	42
Issue number	2
DOIs	https://doi.org/10.1016/j.jeurceramsoc.2021.07.064
State	Published - Feb 2022
Externally published	Yes

Funding

This work was funded through the Office of Naval Research Award #N000141712280 with program manager Dr. David Shifler and the National Science Foundation DMREF: Collaborative Research: GOALI: Accelerating Discovery of High Entropy Silicates for Extreme Environments, Award #1921973 . The authors would like to acknowledge the Nanoscale Materials Characterization Facility at the University of Virginia for supporting this research through characterization equipment.

Funders	Funder number
National Science Foundation	1921973
Office of Naval Research	000141712280
University of Virginia

Keywords

Alumina
Environmental barrier coatings
High-velocity steam
Reaction enthalpy
Recession

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10.1016/j.jeurceramsoc.2021.07.064

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title = "Quantitative evaluation of (0001) sapphire recession in high-temperature high-velocity steamjet exposures",

abstract = "High-temperature high-velocity steam exposures of (0001) sapphire coupons were performed at temperatures of 1200 °C–1450 °C to determine the quantitative capability of the steamjet apparatus. Recession results were compared to calculated values of Al(OH)3 (g) mass transfer rates based on laminar flow models and available thermodynamic data for Al(OH)3 (g). Linear material volatilization rates and a strong gas velocity dependence on the reaction depth confirmed that the Al2O3 reaction was controlled by a gas-phase diffusion process. The temperature dependence for the steam reaction agreed with thermodynamic calculations and with the literature, confirming that Al(OH)3 (g) transport through a gas boundary layer represents the rate-limiting step for Al2O3 volatilization in steam. The steamjet experimental setup can thus be utilized for determination of steam-oxide reaction thermodynamics given known steam flow conditions. Steamjet test recession results for simple oxides are discussed for comparison with behavior of complex oxides that form porous product layers, which are not yet well understood.",

keywords = "Alumina, Environmental barrier coatings, High-velocity steam, Reaction enthalpy, Recession",

author = "Ridley, {Mackenzie J.} and Opila, {Elizabeth J.}",

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year = "2022",

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doi = "10.1016/j.jeurceramsoc.2021.07.064",

language = "English",

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AU - Ridley, Mackenzie J.

AU - Opila, Elizabeth J.

PY - 2022/2

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N2 - High-temperature high-velocity steam exposures of (0001) sapphire coupons were performed at temperatures of 1200 °C–1450 °C to determine the quantitative capability of the steamjet apparatus. Recession results were compared to calculated values of Al(OH)3 (g) mass transfer rates based on laminar flow models and available thermodynamic data for Al(OH)3 (g). Linear material volatilization rates and a strong gas velocity dependence on the reaction depth confirmed that the Al2O3 reaction was controlled by a gas-phase diffusion process. The temperature dependence for the steam reaction agreed with thermodynamic calculations and with the literature, confirming that Al(OH)3 (g) transport through a gas boundary layer represents the rate-limiting step for Al2O3 volatilization in steam. The steamjet experimental setup can thus be utilized for determination of steam-oxide reaction thermodynamics given known steam flow conditions. Steamjet test recession results for simple oxides are discussed for comparison with behavior of complex oxides that form porous product layers, which are not yet well understood.

AB - High-temperature high-velocity steam exposures of (0001) sapphire coupons were performed at temperatures of 1200 °C–1450 °C to determine the quantitative capability of the steamjet apparatus. Recession results were compared to calculated values of Al(OH)3 (g) mass transfer rates based on laminar flow models and available thermodynamic data for Al(OH)3 (g). Linear material volatilization rates and a strong gas velocity dependence on the reaction depth confirmed that the Al2O3 reaction was controlled by a gas-phase diffusion process. The temperature dependence for the steam reaction agreed with thermodynamic calculations and with the literature, confirming that Al(OH)3 (g) transport through a gas boundary layer represents the rate-limiting step for Al2O3 volatilization in steam. The steamjet experimental setup can thus be utilized for determination of steam-oxide reaction thermodynamics given known steam flow conditions. Steamjet test recession results for simple oxides are discussed for comparison with behavior of complex oxides that form porous product layers, which are not yet well understood.

KW - Alumina

KW - Environmental barrier coatings

KW - High-velocity steam

KW - Reaction enthalpy

KW - Recession

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ER -

Quantitative evaluation of (0001) sapphire recession in high-temperature high-velocity steamjet exposures

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