Evolution with Temperature of Crystalline and Amorphous Phases in Porcelain Stoneware
Porcelain stoneware tile is a ceramic building material characterised by high technological properties, especially regarding water absorption, chemical and frost resistance, bending strength and abrasion resistance. Since mineralogy is one of the main factors affecting the mechanical properties of p...
| Autores: | , , , , |
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| Formato: | artículo |
| Fecha de publicación: | 2009 |
| País: | España |
| Recursos: | Consejo Superior de Investigaciones Científicas (CSIC) |
| Repositorio: | DIGITAL.CSIC. Repositorio Institucional del CSIC |
| OAI Identifier: | oai:digital.csic.es:10261/62896 |
| Acesso em linha: | http://hdl.handle.net/10261/62896 |
| Access Level: | acceso abierto |
| Palavra-chave: | Mullite Rietvel X-ray diffraction porcelain stoneware |
| Resumo: | Porcelain stoneware tile is a ceramic building material characterised by high technological properties, especially regarding water absorption, chemical and frost resistance, bending strength and abrasion resistance. Since mineralogy is one of the main factors affecting the mechanical properties of porcelain stoneware, a complete determination and quantification of the mineral and amorphous phases is of special importance in the study of porcelain stoneware tiles. In the present work, a reference industrial composition (50% kaolinitic clay, 40% feldspar and 10% quartz) of porcelain stoneware tiles fired at different temperatures (400º-1400ºC) was characterised by X-ray powder diffraction combined with quantitative full-phase analysis using the Rietveld method, including amorphous content. The green composition contained albite, microcline and muscovite as fluxing agents, which start to decompose at low temperatures (400º-800ºC range) and are completely dissolved above 1200ºC. The mullite phase is formed from 1100º to 1230ºC and at the latter temperature, quartz particles start to dissolve. Studies of mineralogical evolution have revealed that the high heating rate (45-50ºC/min) required in ceramic tile manufacture leads to significant differences in comparisons with whiteware ceramics fired at a lower heating rate (10ºC/min). Thus, the formation of mullite in porcelain stoneware occurs at higher temperatures (1100ºC) whereas the transformation of β-quartz to β-cristobalite does not take place. The experimental results of this study show that qualitative mineralogical analysis, based on the intensity of a particular diffraction peak for each crystalline phase, is a suitable methodology to obtain preliminary knowledge of mineralogical changes with temperature. |
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