Change of mineralogical structure, plasticity and physical properties of ceramic clays caolinitic and illitic at different temperatures

Every raw material used in ceramic production has different effects on the structure of the product. Feldspar, for instance, enables sintering, while dolomite-quartz yields skeleton and porosity and clay minerals provides handling thanks to their plasticity. The minerals that compose the clay have different impact on the rheological properties and firing behaviours of ceramic products during the production stage. In this study, the change in the plasticity and physical-mechanical characteristics of clays composed of kaolin and illite was analysed by firing them raw and at various temperatures. During the production of the ceramic products, five different clay samples containing kaolin, mica mineral, illite, muscovite, quartz and montmorillonite were used. Plasticity, thermal and physical-mechanical characteristics of raw clay samples and plasticity, mineralogical development and physical-mechanical characteristics of those fired at various temperatures were analysed. According to the results, it was seen that kaolin clays don?t have plasticity characteristics and that the existence of kaolin with illite mineral cause the clay to show plasticity character. It was also noted that clays with lower illite content and higher kaolin content lose their plasticity characteristics by drying, while kaolin clays with higher illite content lose their plasticity characteristics when their structural water is lost at higher temperatures. It was concluded that the change ceramic properties of clays undergo raw and at different temperatures varies depending on their mineral content. Key Words: DTA, Low Temperature, Illite, Kaolin, Plasticity, Grading, XRD