CVD mullite coatings in high-temperature, high-pressure air-H2O

J. Alien Haynes, Michael J. Lance, Kevin M. Cooley, Mattison K. Ferber, Richard A. Lowden, David P. Stinton

Research output: Contribution to journalArticlepeer-review

62 Scopus citations

Abstract

Crystalline mullite was deposited by chemical vapor deposition (CVD) onto SiC/SiC composites overlaid with CVD SiC. Specimens were exposed to isothermal oxidation tests in high-pressure air+H2O at 1200 °C. Unprotected CVD SiC formed silica scales with a dense amorphous inner layer and a thick, porous, outer layer of cristobalite. Thin coatings (approximately 2 μm) of dense CVD mullite effectively suppressed the rapid oxidation of CVD SiC. No microstructural evidence of mullite volatility was observed under these temperature, pressure, and low-flow-rate conditions. Results of this preliminary study indicate that dense, crystalline, high-purity CVD mullite is stable and protective in low-velocity, high-pressure, moisture-containing environments.

Original languageEnglish
Pages (from-to)657-659
Number of pages3
JournalJournal of the American Ceramic Society
Volume83
Issue number3
DOIs
StatePublished - 2000

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