authors |
Santana, LNL; Gomes, J; Menezes, RR; Neves, GA; Lira, HL; Segadaes, AM |
nationality |
International |
journal |
APPLIED CLAY SCIENCE |
author keywords |
Clays; Heating parameters; Phase transformations; Mullite |
keywords |
MULLITE FORMATION; THERMAL-TREATMENT; RAW-MATERIAL; PORCELAIN; CERAMICS; KAOLINITE; MONTMORILLONITE; BENTONITES; MICROWAVE; EVOLUTION |
abstract |
Knowledge about the relationships between mineralogical and microstructural characteristics of clays and the transformations that occur during firing is of fundamental importance for various industries, enabling the manufacture of better quality products and widespread use of those raw materials. The aim of this study was to interpret phase development and morphological transformations in clays subjected to different heat treatments, with emphasis on the effect of impurities (iron and alkalis), temperature and heating rate. The experiments were carried out using conventional and microwave heating, with characterization by X-ray diffraction and scanning electron microscopy. The interpretation of the results based on the mullite-silica-leucite phase diagram showed that crystallization and grain growth are closely related to the amount and viscosity of the liquid phase present at the firing temperature, which vary with the composition and can be predicted by the phase diagram. Faster heating rates tend to slightly delay the establishment of equilibrium, which appears to have special bearing on the liquid phase viscosity, hence, on grain growth. As a consequence, the resulting microstructure contains mullite needles that are shorter and more uniform in size. (C) 2016 Elsevier B.V. All rights reserved. |
publisher |
ELSEVIER SCIENCE BV |
issn |
0169-1317 |
year published |
2017 |
volume |
135 |
beginning page |
325 |
ending page |
332 |
digital object identifier (doi) |
10.1016/j.clay.2016.10.014 |
web of science category |
Chemistry, Physical; Materials Science, Multidisciplinary; Mineralogy |
subject category |
Chemistry; Materials Science; Mineralogy |
unique article identifier |
WOS:000390621800035
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ciceco authors
impact metrics
journal analysis (jcr 2017):
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journal impact factor |
3.641 |
5 year journal impact factor |
3.616 |
category normalized journal impact factor percentile |
75.255 |
dimensions (citation analysis):
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altmetrics (social interaction):
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