Acicular Mullite Crystals in Vitrified Kaolin
Resource
Journal of the American Ceramic Society 87 (10): 1843-1847
Journal
Journal of the American Ceramic Society
Journal Volume
87
Journal Issue
10
Pages
1843-1847
Date Issued
2004
Date
2004
Author(s)
Abstract
The microstructure of vitrified kaolin ceramic tapes has been studied via scanning and transmission electron microscopy (SEM and TEM). The sintered samples contained crystalline phase of predominantly stoichiometric mullite (3Al2O3·2SiO2), which consisted of high aspect ratio, acicular crystals that are often referred to as secondary mullite. These crystals were interlocked and embedded in an aluminosilicate glass matrix of inhomogeneous composition. The glass matrix contained an average of ∼3.63 wt% K as determined by energy-dispersive X-ray analysis (EDS), whose composition could be approximated to 5Al2O 3·16SiO2·0.1MgO·0.3K 2O·0.15TiO2·0.12Fe2O 3. The acicular crystals have approximately the stoichiometric composition of Al2O3:SiO2 = 3:2. They have grown along a specific crystallographic orientation along the [001] axis. The crystal growth front exhibited facetting on the (110) planes with microfacetting on both the (100) and (010) planes.
Other Subjects
Ceramic products; Crystallography; Crystals; Energy dispersive spectroscopy; Glass; Scanning electron microscopy; Stoichiometry; Transmission electron microscopy; X ray analysis; Acicular crystals; Glass matrix; Microfacetting; Mullites; Kaolin
Type
journal article
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