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http://hdl.handle.net/10773/20077
Title: | Directionally solidified eutectic and off-eutectic mullite zirconia fibres |
Author: | Carvalho, R. G. Pires, M. S. Fernandes, A. J. S. Silva, R. F. Costa, F. M. |
Keywords: | FLOATING-ZONE TECHNIQUE GROWN AL2O3-ZRO2(Y2O3) EUTECTICS MECHANICAL-PROPERTIES RESIDUAL-STRESSES CERAMICS AL2O3-ZRO2-SIO2 MICROSTRUCTURE Y2O3-ZRO2 STABILITY COMPOSITE |
Issue Date: | 2013 |
Publisher: | ELSEVIER SCI LTD |
Abstract: | Eutectic and off-eutectic mullite-zirconia fibres were grown by LFZ (laser floating zone) directional solidification. The microstructure of the mullite-zirconia eutectic fibres varies from planar coupled eutectic (1 mm/h pulling rate) through mullite columnar growth with coarse zirconia inclusions (10 mm/h pulling rate) to faceted mullite eutectic dendrites, which enclose a dispersion of fine zirconia fibrils (100-500 mm/h pulling rates). Near-equilibrium conditions determine the crystallization of monoclinic zirconia and the absence of any amorphous phase, whereas for higher speeds the tetragonal structure is retained and a residual liquid is kept after the eutectic solidification. Similar structural and morphological characteristics are displayed by the mullite-rich off-eutectic composition added to the development of prismatic crystals of mullite primary phase. In opposition, heavy constitutional supercooling takes place in the case of the zirconia-rich off-eutectic fibres, where equiaxed zirconia dendrites soon form as a primary phase, leaving a non-equilibrium mixture of alumina and sillimanite as interdendritic constituent. (C) 2012 Elsevier Ltd. All rights reserved. |
Peer review: | yes |
URI: | http://hdl.handle.net/10773/20077 |
DOI: | 10.1016/j.jeurceramsoc.2012.09.032 |
ISSN: | 0955-2219 |
Publisher Version: | 10.1016/j.jeurceramsoc.2012.09.032 |
Appears in Collections: | CICECO - Artigos |
Files in This Item:
File | Description | Size | Format | |
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Directionally solidified eutectic and off-eutectic mullite-zirconia fibres_10.1016j.jeurceramsoc.2012.09.032.pdf | 2.65 MB | Adobe PDF |
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