A MgO-Al₂O₃-SiO₂ system was used in order to prepare glass-ceramic glazes with high-hardness applicable to ceramic tiles. The glass-ceramic glazes were prepared by adding the fluxes CaO and B₂O₃ and the nucleating agent TiO₂ to the glaze. The crystallization behavior of the glaze was calculated by a non-isothermal thermal analysis via a Differential Thermal Analysis (DTA), and the glaze was heat treated at the crystallization temperature (T_p2). The activation energy (E) and the Avrami constant (n) of the glaze with 8wt% TiO₂ substitution were 177.07 kJ/mol and 2.65, respectively. X-ray diffraction analysis (XRD) showed that the cordierite and anorthite crystal phases were formed and the karrooite crystal phases grew with increasing TiO₂ substitution. The degree of crystallinity increased as the amount of TiO₂ increased and the degree of crystallinity was 76.5% in the glaze with 8 wt% TiO₂ substitution. In the Scanning Electron Microscope (SEM) analysis, the cordierite and anorthite crystal phases were the largest in the glaze with 8wt% TiO₂ substitution and rapidly decreased in the glaze with 12 wt% TiO₂ substitution. As a result, Vickers hardness of the glaze showed a high value of 7.10 GPa at the glaze with 8wt% TiO₂ substitution after heat treatment at 1,010 ^oC.

Keywords: Glass-Ceramic Glaze, Cordierite, TiO₂ nucleation agent, Hardness, Avrami constant