Microstructural development, phase stability, and toughening in mullite-matrix composites
Thesis/Dissertation
·
OSTI ID:7292666
Mullite-matrix composites with partially stabilized zirconia and/or SiC whiskers were fabricated by hot pressing of powders prepared from Al, Si, Zr, and Mg (or Y) alkoxide precursors by a sol-gel process. A series of studies were conducted on microstructural evolution, oxidation behavior, and toughening mechanisms, in order to extend the knowledge in these areas and provide a basis for the future development of these materials. It was found that, during hot pressing, mullite developed from an intermediate Al-Si spinel phase, while zirconia could develop by (1) nucleation, growth and subsequent transformation of cubic ZrO{sub 2} particles from the amorphous matrix; (2) dissolution and reprecipitation from mullite grains; (3) decomposition from zircon (ZrSiO{sub 4}), which had formed as an intermediate phase. The microstructural development in hot pressed composites was found to be significantly different from that in heat treated powders. The oxidation behavior of SiC whiskers in various matrices was investigated at temperatures ranging from 1,000 to 1,350C for up to 1,000 hours. Finally, possible toughening mechanisms in mullite matrix composites were addressed.
- Research Organization:
- Illinois Univ., Urbana, IL (United States)
- OSTI ID:
- 7292666
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
36 MATERIALS SCIENCE
360602* -- Other Materials-- Structure & Phase Studies
360603 -- Materials-- Properties
CARBIDES
CARBON COMPOUNDS
CHALCOGENIDES
COMPOSITE MATERIALS
CRYSTAL STRUCTURE
FABRICATION
FRACTURE PROPERTIES
HOT PRESSING
INORGANIC ION EXCHANGERS
ION EXCHANGE MATERIALS
MATERIALS
MATERIALS WORKING
MATRIX MATERIALS
MECHANICAL PROPERTIES
MICROSTRUCTURE
MINERALS
MULLITE
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PHASE STUDIES
POWDERS
PRESSING
SILICON CARBIDES
SILICON COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
ZIRCONIUM COMPOUNDS
ZIRCONIUM OXIDES
360602* -- Other Materials-- Structure & Phase Studies
360603 -- Materials-- Properties
CARBIDES
CARBON COMPOUNDS
CHALCOGENIDES
COMPOSITE MATERIALS
CRYSTAL STRUCTURE
FABRICATION
FRACTURE PROPERTIES
HOT PRESSING
INORGANIC ION EXCHANGERS
ION EXCHANGE MATERIALS
MATERIALS
MATERIALS WORKING
MATRIX MATERIALS
MECHANICAL PROPERTIES
MICROSTRUCTURE
MINERALS
MULLITE
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PHASE STUDIES
POWDERS
PRESSING
SILICON CARBIDES
SILICON COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
ZIRCONIUM COMPOUNDS
ZIRCONIUM OXIDES