EFFECTS OF NUCLEATING-AGENTS ON DIOPSIDE CRYSTALLIZATION IN NEW GLASS-CERAMICS FOR TILE-GLAZE APPLICATION

The effect of crystallization produced by addition of TiO2, ZrO2 and P 2O5 oxides to glass-ceramic of the system CaO-MgO-SiO2 was studied usi ng structural and thermal techniques. The devitrification process was independent of thermal treatment. X-ray diffraction studies performed on the glass-ceramic system indicated that diopside crystalline phase was more thermodynamically favourable than other phases. The effect of the nucleating agent depends on its nature: TiO2 decreased the activa tion energy while P2O5 and ZrO2 did not. SEM analysis of the doped gla ss-ceramics showed randomly distributed crystals with significant dime nsional variations from those of the undoped system. All these formula tions, showing a high crystallization rate, and a fast heating rate, c an be used as tile glazes and/or tile-glaze components.