75908 20191126134629.0 doi 10.1016/j.clay.2017.11.025 sideral 103756 ART-2018-103756 eng Laita, Elisa Mineral and textural transformations in aluminium-rich clays during ceramic firing 2018 Access copy available to the general public Unrestricted The aim of this study has been to analyse the mineralogical and textural transformations of a set of aluminium-rich shales of interest for refractory and ceramic uses, fired from 800 °C to 1300 °C. To that end, raw and fired samples were analysed by X-ray diffraction, transmitted light microscopy, field emission scanning electron microscopy, and transmission electron microscopy. Raw samples comprise variable proportions of illite, pyrophyllite, orthoclase, quartz, kaolinite, mixed-layer I-Sm, and organic matter. At temperatures below 800 °C, kaolinite, mixed-layer I-Sm, and organic matter are destabilized, indicating that they are the least stable phases in the firing process. Illite, pyrophyllite, and orthoclase remain until 1000 °C and show a broader stability field during firing than in natural environments. Quartz persists throughout the entire firing process, although it is partly replaced by vitreous phase. Hematite crystallizes at 900 °C. Vitrification begins at 1000 °C, marking the first significant textural change. From 1000 °C mullite starts to crystallize from the Si- and Al-rich vitreous phase. The mullite composition is not stoichiometric and probably as temperature increases Si is partially replaced by Al, Fe and Ti in the structure. Nevertheless, with the increase of the firing temperature, the mullite composition is closer to the theoretical composition and also to that of natural mullites. Furthermore its crystal thickness increases with temperature up to 70 nm. info:eu-repo/grantAgreement/ES/MINECO/CGL2013-46169-C2-1-P info:eu-repo/semantics/openAccess by-nc-nd http://creativecommons.org/licenses/by-nc-nd/3.0/es/ 3.89 2018 MATERIALS SCIENCE, MULTIDISCIPLINARY 73 / 293 = 0.249 2018 Q1 T1 MINERALOGY 4 / 29 = 0.138 2018 Q1 T1 CHEMISTRY, PHYSICAL 51 / 148 = 0.345 2018 Q2 T2 0.99 2018 Geology 2018 Q1 Geochemistry and Petrology 2018 Q1 info:eu-repo/semantics/article info:eu-repo/semantics/acceptedVersion (orcid)0000-0002-4970-6333 Bauluz, Blanca Universidad de Zaragoza 2000 120 Universidad de Zaragoza Dpto. Ciencias de la Tierra Área Cristalografía Mineralog. 152 (2018), 284-289 Appl. clay sci. APPLIED CLAY SCIENCE 0169-1317 668348 http://zaguan.unizar.es/record/75908/files/texto_completo.pdf Postprint 88236 http://zaguan.unizar.es/record/75908/files/texto_completo.jpg?subformat=icon icon Postprint oai:zaguan.unizar.es:75908 articulos driver 2019-11-26-13:40:09 ARTICLE