Experimental porcelain stoneware has been formed by slip casting and sintered by rate controlled dilatometry. Shrinkage has been measured at various constant heating rates up to 1300 oC by dilatometry. A kinetic field for stoneware firing has been set up by connecting points of equal density on the sintering rate curves to determine the activation energy for densification and to calculate optimum firing cycles. The activation energy for densification has been calculated from the slope of the isodensity curves. It has been observed that the activation energy increases with progressive sintering i.e. 470-497 kJ/mol for the intermediate sintering stage (1100-1225 oC) accounting for most of the densification. The abrupt shrinkage and low activation energy values during the intermediate sintering stage suggest a viscous flow mechanism of densification. The final sintering stage responsible for a reduced densification rate showed a lower 313 kJ/mol activation energy.

Keywords: Activation energy, Densification process, Dilatometric behavior, Constant heating rates.