Synthesis of glass-ceramic glazes in the ZnO–Al2O3–SiO2–ZrO2 system

Glazes in the ZnO–Al2O3–SiO2–ZrO2 system with crystallization ability of gahnite (ZnO·Al2O3) and β-quartz solid solution (βqss) were synthesized. The compositions were designed based on calcium and magnesium oxide replacement (from a CaO–MgO–Al2O3–SiO2 glass-ceramic glaze system) with zinc oxide and simultaneous increasing aluminum oxide. By this replacement, diopside eliminated and co-precipitation of gahnite and zirconium silicate observed. However, a little addition of Li2O changes the crystallization path by precipitation of βqss and willemite (2ZnO·SiO2) at low temperatures (800–900 °C) which dissolved into glaze by development of firing temperature. The experiments showed that while the micro-hardness of gahnite-based glass-ceramic glazes is almost equal with the diopside based one, it is more than the traditional floor tile glazes.