Production and characterisation of granulated frit to achieve anorthite based glass–ceramic glaze

For the development of matt-transparent glass–ceramic coating applied on the porcelain tile, the CaO–Al2O3–SiO2 system was studied. Sinterization and devitrification behavior of granulated frits and viscosity change with temperature were analyzed by combining the data that belong to differential thermal analysis and heating microscope analysis. Characterization by X-ray diffraction (XRD) combined with scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) microanalysis show that needle like crystals of anortite is formed. Crystal size of anorthite was adjusted by modifying composition. Since anorthite crystals cannot be made smaller than wavelength of light in the studied system, anorthite crystal size is increased to reduce light refraction so that light is homogeneously distributed. Anorthite crystals with low refractive index crystallized as rod-like crystals and distributed homogenously in the system. Thus, the light is allowed to pass through the substrate and as a conclusion transparent appearance of the glaze is increased.