Nucleation mechanisms in chemically vapor-deposited mullite coatings on SiC

Journal Article · Thu Jul 01 00:00:00 EDT 1999 · Journal of Materials Research

DOI:https://doi.org/10.1557/JMR.1999.0395· OSTI ID:686865

Hou, P; Basu, S N; Sarin, V K ^[1]

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1. Department of Manufacturing Engineering, Boston University, 15 St. Marys Street, Boston, Massachusetts 02215 (United States)

Dense, uniform, and adherent chemically vapor-deposited mullite coatings were deposited on SiC substrates using the AlCl{sub 3}{endash}SiCl{sub 4}{endash}H{sub 2}{endash}CO{sub 2} system. Typical coating morphology consisted of a thin interfacial layer of {gamma}{endash}Al{sub 2}O{sub 3} nanocrystallites embedded within a vitreous SiO{sub 2}-based matrix. When a critical Al/Si ratio of 3.2{plus_minus}0.29 was reached within this nanocrystalline layer, mullite crystals nucleated and grew as columnar grains. The thickness of the nanocrystalline layer decreased as the input AlCl{sub 3}/SiCl{sub 4} ratio was increased. In all cases, the Al/Si composition in the coating increased from the coating/substrate interface to the coating surface. Critical factors leading to the nucleation and growth of mullite crystals are discussed in this article. {copyright} {ital 1999 Materials Research Society.}

• Research Organization: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 686865
• Journal Information: Journal of Materials Research, Vol. 14, Issue 7; Other Information: PBD: Jul 1999
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CORROSION PROTECTION
SILICON COMPOUNDS
CARBON COMPOUNDS
ALUMINIUM COMPOUNDS
OXYGEN COMPOUNDS
SILICON CARBIDES
SILICON OXIDES
ALUMINIUM OXIDES
COATINGS
CHEMICAL VAPOR DEPOSITION
GRAIN GROWTH
INTERFACES
MICROSTRUCTURE