Laita Florian, Elisa Bauluz Lázaro, Blanca Transformaciones minerales durante los procesos de cocción de arcillas alumínicas y su relación con propiedades físicas de interés Mineralogical and textural transformations and changes in physical properties of three shales fired from 800 to 1300ºC have been studied. Initially these samples were formed by variable proportions of illite, pyrophyllite, orthoclase, quartz, kaolinite, mixed layers I/S and organic matter. Raw and fired samples were analysed by X-ray diffraction, transmitted light microscopy, field emission scanning electron microscopy and transmission electron microscopy. Kaolinite, mixed layers I/S and organic matter were destabilized at temperatures below 800°C indicating that they are the least stable phases to the firing process. Illite, pyrophyllite and orthoclase remain until 1000ºC and they show a larger stability field during the ceramic process than in natural environments. Quartz remains during all the firing process, although it is partly replaced by vitreous material. When temperature increases, hematite and mullite crystallize and the vitrification starts from 1000ºC. This vitreous phase is the precursor of mullite. Changes in colour (grey-orange-brown) are due to the loss of organic matter, to the formation of hematite and its subsequent destabilization. Variations in linear contraction, density, total porosity and in average pore size are related to the destabilization of the different phases, the progress of vitrification and the crystallization of mullite. spa Universidad de Zaragoza Zaragoza 2016

http://zaguan.unizar.es/record/58756/files/TAZ-TFM-2016-230.pdf;

Imported from Invenio.