Influence of firing temperature on the ceramic properties of Triassic clays from Tunisia

This study deals with the mineralogical, physico-chemical, thermal analysis and technological of representative Triassic clay in the south-Eastern Tunisia, in order to use in the faience ceramic. That is why the study had recourse to several quantitative and qualitative techniques of analysis; chemical analysis, mineralogical study, thermal analyses and analyses of geotechnical traits. The data collected from these techniques show that illite and kaolinite are the major clay phases. The accessory minerals detected in powdered rock are quartz, dolomite and hematite. The samples were dry pressed and sintered at temperatures ranging from 850 to 1150 °C. The samples were characterised before and after firing. The densification was measured by three parameters: firing shrinkage, water absorption, and resistance to the inflection. A series of phase transformations takes place during sintering is governed by different mechanisms according to the temperature, which play an important role on the densification. The neomineralization processes were investigated principally by X-ray diffraction. The development of resistance to the inflection and reduction in water absorption on samples products from this Triassic clay material was noticed at elevated temperatures due to enhanced vitrification. Given the mineralogy and physico-chemical characteristics of this clay deposits could be used for the manufacture of faience ceramic production.