Study on Crystallization of the Glaze for Tiles by Substitution of TiO₂, Al₂O₃ and ZrO₂ Nucleating Agents.

A crystalline glaze is more chemically stable than a general glaze because it forms a fine and regular crystalline grain in vitreous matrix, and they are mainly used for floor or wall tiles because the surface of the glaze is smooth and has excellent abrasion resistance. In this paper, high hardness crystallized glazes with nano-sized crystal grains were prepared by substituting the nucleating agents TiO₂, Al₂O₃ and ZrO₂ in the glaze. The crystal glazes were obtained by preparing a glaze frit based on the composition SiO₂-ZrO₂-ZnO-CaO, according to the substitution amounts of TiO₂, Al₂O₃ and ZrO₂, and firing at 1100 °C and 1150 °C. X-ray diffraction (XRD) analysis was performed to observe the resulting crystal phase depending on the nucleating agent. The crystal size of the crystallized glaze produced was confirmed to be nano-sized through field emission scanning electron microscope (FE-SEM) analysis. The hardness of the crystallized glazes prepared by adding the nucleating agent was tested using the Vickers hardness measurement method, and was found to be slightly higher than that of the crystallized glaze made of ordinary glaze frit. Thus, nano-crystalline glazes of high hardness were prepared by controlling the nucleating agent and substitution amount.