Zirconium glazes used in fast single fired wall tile manufacture. Part 2: empirical model for fitting experimental data from devitrification process

Abstract

Firing ceramic tiles coated with frits (glass) containing a suitable proportion of zirconium for producing white glaze coatings gives rise to devitrification in which tetragonal zirconium oxide and zircon (zirconium silicate) crystals are sequentially formed. The use of an empirical model was tested for fitting the experimental results. The model was obtained by assuming that the arising transformations in the sysetm studied (crystallisation of zirconium to zirconia and conversion of zirconia to zirconium silicate) develop analogously to those of a system of two simultaneous and consecutive first order irreversible chemical reactions. The proposed model allows the proportion of zirconium that crystallises during firing to be satisfactorily reproduced.