Thermal behaviour of ceramics obtained from the kaolinitic clays of Terra Alta, Catalonia, Spain.
The thermal properties and evolution of mineralogy and colour of kaolinitic clay from the Terra Alta region were studied. The mineralogy of these materials consists mainly of kaolinite (13-27 mass%) and quartz (48-86 mass%). Minor illite, hematite, K-feldspar and calcite also occur. The linear expan...
| Autores: | , , , |
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| Tipo de recurso: | artículo |
| Estado: | Versión aceptada para publicación |
| Fecha de publicación: | 2021 |
| País: | España |
| Institución: | Varias* (Consorci de Biblioteques Universitáries de Catalunya, Centre de Serveis Científics i Acadèmics de Catalunya) |
| Repositorio: | Recercat. Dipósit de la Recerca de Catalunya |
| OAI Identifier: | oai:recercat.cat:2445/180610 |
| Acceso en línea: | https://hdl.handle.net/2445/180610 |
| Access Level: | acceso abierto |
| Palabra clave: | Minerals Ceràmica Minerals d'argila Terra Alta (Catalunya) Pottery Clay minerals Terra Alta (Catalonia) |
| Sumario: | The thermal properties and evolution of mineralogy and colour of kaolinitic clay from the Terra Alta region were studied. The mineralogy of these materials consists mainly of kaolinite (13-27 mass%) and quartz (48-86 mass%). Minor illite, hematite, K-feldspar and calcite also occur. The linear expansion and absorption curves were used to predict the optimal firing temperature of the raw clays. During firing, from 1100 °C the water absorption decreases steeply, due to an increase in liquid phase, which penetrates into the pores and close the porosity. At this temperature, the firing shrinkage increases progressively. The fired clays are mainly composed of quartz, cristobalite and mullite, with minor hematite and rutile. Mullite starts to appear at 1050-1100 °C. SEM observations show that porosity decreases with the firing temperature. The colour properties were measured in the raw clays and in the fired bricks at different temperatures. The lightness, L*, is lower in the fired test pieces respect to the natural clays. This colour varies according to the hematite content, being from white to reddish in the fired samples. |
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