Reaction densification of {alpha}{prime}-SiAlON. 2: Densification behavior
- Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Materials Science and Engineering
Reaction hot-pressing behavior of {alpha}-Si{sub 3}N{sub 4}, Al{sub 2}O{sub 3}, AlN, and M{sub 2}O{sub z} powder mixtures (M = Li, Mg, Ca, Y, Nd, Sm, Gd, and Yb) forming {alpha}{prime}-SiAlON has been studied. Five characteristic temperatures are found to control the densification behavior of these materials. The densification proceeded in three major stages. The first two stages were formation of ternary oxide eutectic and wetting of majority nitride powder. The third stage involved dissolution/melting of intermediate phase. Variation from this behavior sometimes occurs due to localization of wetting liquid at AlN, extremely high melting/dissolution temperature of Mg{sub 2}Al{sub 4}-Si{sub 5}O{sub 18} and Nd and Sm melilite, and secondary precipitation Dy-{alpha}{prime}-SiAlON. The dominant densification mechanism was found to be massive particle rearrangement, irrespective of the wetting and dissolution/melting behavior. The efficiency of this mechanism is mostly affected by the amount of available liquid and less by its viscosity. Fully dense, single-phase ceramics were obtained in all cases exceed Mg when hot-pressed at a constant heating rate to 1,750 C, and considerably lower temperatures for Li, Ca, Gd, Dy, Er, and Yb-SiAlON when held isothermally.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 79764
- Journal Information:
- Journal of the American Ceramic Society, Journal Name: Journal of the American Ceramic Society Journal Issue: 3 Vol. 78; ISSN 0002-7820; ISSN JACTAW
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ALUMINIUM NITRIDES
ALUMINIUM OXIDES
CALCIUM OXIDES
DISSOLUTION
DOPED MATERIALS
DYSPROSIUM OXIDES
ERBIUM OXIDES
EUTECTICS
GADOLINIUM OXIDES
HOT PRESSING
LIQUIDS
LITHIUM OXIDES
MAGNESIUM OXIDES
NEODYMIUM OXIDES
SAMARIUM OXIDES
SHRINKAGE
SILICON NITRIDES
TEMPERATURE DEPENDENCE
WETTABILITY
YTTERBIUM OXIDES
YTTRIUM OXIDES