Irreversible Dilatometry as a Tool for Body Composition and Firing Schedule Design in Traditional Ceramics

Abstract

Traditional ceramic products are made up of clay, quartz and feldspar raw materials. The technical properties of these products depend on physico-chemical aspects of ingredient materials, their reaction kinetics during firing and ultimate microstructure development. Irreversible dilatometry is an uncommon but powerful technique to study the densification behaviour of ceramics. Differential coefficient of expansion (DCE) is the derivative of percentage of linear change (PLC). DCE is taken as indicator of phase development and other thermal reactions. One white burning and one red burning clay commonly used for manufacturing ceramic tile bodies were studied for irreversible dilatometry. The dilatometric behaviour of individual clays and their combined effect on a ceramic tile body were correlated. Red clay was found to be more thermally stable than white clay in 550°-650°C temperature range because of lesser dimensional vibrations. DCE curves of experimental bodies illustrated that the bodies were in the thermally induced dimensional vibration phases in the temperature ranges of 500 °-650°C and 800°-1000°C, hence these regions are critical and taken care while designing firing schedule. The study showed that the improved performance obtained by irreversible dilatometry can be utilized for designing compatible firing schedule and to achieve better productivity.