Crystallization of MgO-Al/sub 2/O/sub 3/-SiO/sub 2/-ZrO/sub 2/ glasses
The crystallization of MgO-Al/sub 2/O/sub 3/-SiO/sub 2/-ZrO/sub 2/ glasses at 1000/sup 0/C was studied. Isothermal heat treatments of a cordierite-based glass (2MgO.2Al/sub 2/O/sub 3/.5SiO/sub 2/ equal to Mg/sub 2/Al/sub 4/Si/sub 5/O/sub 18/) with 7 wt% ZrO/sub 2/ produced surface crystallization of ..cap alpha..-cordierite and tetragonal ZrO/sub 2/ (t-ZrO/sub 2/). These phases advanced into the glass by cocrystallization of t-ZrO/sub 2/ rods in an ..cap alpha..-cordierite matrix with a well-defined orientation relation. The t-ZrO/sub 2/ were unstable with respect to diffusional breakup (a Raleigh instability) and decomposed into rows of aligned ellipsoidal and spheroidal particles. The t-ZrO/sub 2/ was very resistant to transformation to monoclinic symmetry. With a similar glass containing 15 wt% ZrO/sub 2/, surface crystallization of ..cap alpha..-cordierite and t-ZrO/sub 2/ was accompanied by internal crystallization of t-ZrO/sub 2/ dendrites. Transformation of the dendrites to monoclinic symmetry was observed under some conditions.
- Research Organization:
- Dept. of Metallurgy and Materials Science, Case Western Reserve Univ., Cleveland, OH 44106
- OSTI ID:
- 5743546
- Journal Information:
- J. Am. Ceram. Soc.; (United States), Journal Name: J. Am. Ceram. Soc.; (United States) Vol. 69:3; ISSN JACTA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360202* -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
360602 -- Other Materials-- Structure & Phase Studies
ALKALINE EARTH METAL COMPOUNDS
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CHALCOGENIDES
CRYSTAL STRUCTURE
CRYSTALLIZATION
CRYSTALS
DENDRITES
GLASS
GRAIN ORIENTATION
MAGNESIUM COMPOUNDS
MAGNESIUM OXIDES
MICROSTRUCTURE
ORIENTATION
OXIDES
OXYGEN COMPOUNDS
PARTICLES
PHASE TRANSFORMATIONS
SILICON COMPOUNDS
SILICON OXIDES
SYMMETRY
TRANSITION ELEMENT COMPOUNDS
VERY HIGH TEMPERATURE
ZIRCONIUM COMPOUNDS
ZIRCONIUM OXIDES