Oxidation behavior of SiC-whisker-reinforced alumina-zirconia composites
- Laboratoire de Physique des Materiaux, Centre National de la Recherche Scientifique, 92195 Meudon (FR)
This paper reports that during high-temperature oxidation in air, SiC-whisker-reinforced Al{sub 2}O{sub 3}-ZrO{sub 2} composites degrade by the formation of a whisker-depleted mullite-zirconia scale. The reaction kinetics have been studied as a function of time and temperature for composites with whiskers preoxidized for different times. The evolution of the microstructure has been investigated by optical, scanning and transmission electron microscopy. Possible reaction mechanisms have been discussed. A model compatible with the authors observations on Al{sub 2}O{sub 3}-ZrO{sub 2}-SiC and the results reported in the literature for Al{sub 2}O{sub 3}-SiC whisker composites is proposed: The oxidation occurs at an internal reaction front. Oxygen diffuses along dislocations and grain boundaries through the mullite scale to react at this front with silicon carbide, thereby forming amorphous silica and graphite. Silica penetrates grain boundaries and further reacts with alumina and zirconia to form mullite and zircon, while the second reaction product, graphite, is oxidized into carbon monoxide when the reaction front moves deeper into the sample.
- OSTI ID:
- 5845196
- Journal Information:
- Journal of the American Ceramic Society; (United States), Journal Name: Journal of the American Ceramic Society; (United States) Vol. 74:8; ISSN JACTA; ISSN 0002-7820
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360202 -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
360205* -- Ceramics
Cermets
& Refractories-- Corrosion & Erosion
360602 -- Other Materials-- Structure & Phase Studies
360604 -- Materials-- Corrosion
Erosion
& Degradation
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
AMORPHOUS STATE
CARBIDES
CARBON
CARBON COMPOUNDS
CHALCOGENIDES
CHEMICAL REACTIONS
CRYSTAL STRUCTURE
CRYSTALS
DIFFUSION
ELECTRON MICROSCOPY
ELEMENTAL MINERALS
ELEMENTS
GRAIN BOUNDARIES
GRAPHITE
INORGANIC ION EXCHANGERS
ION EXCHANGE MATERIALS
MATERIALS
MICROSCOPY
MICROSTRUCTURE
MINERALS
MONOCRYSTALS
MULLITE
NONMETALS
OXIDATION
OXIDE MINERALS
OXIDES
OXYGEN
OXYGEN COMPOUNDS
REINFORCED MATERIALS
SCANNING ELECTRON MICROSCOPY
SILICA
SILICON CARBIDES
SILICON COMPOUNDS
SILICON OXIDES
TEMPERATURE DEPENDENCE
TIME DEPENDENCE
TRANSITION ELEMENT COMPOUNDS
TRANSMISSION ELECTRON MICROSCOPY
WHISKERS
ZIRCONIUM COMPOUNDS
ZIRCONIUM OXIDES