Investigation of the effects of kiln roller waste addition on porcelain tile matte-opaque glazes

Abstract Ceramic tiles reach their final microstructures and acquire their technical properties by firing process after shaping, glazing, and drying processes. The firing process is carried out continuously in roller kilns. In roller kilns, tiles pass through firing zones at different firing temperatures such as preheating, firing, and cooling zones in which different types of rollers are used. deformations such as breakage and deterioration of roller smoothness occur in the kiln roller over time due to high temperature and tile mass. For these reasons, unused kiln rollers are separated into waste and replaced with new ones. In the present study, the purpose was to transform the kiln roller into a value-added product. For this purpose, the use of kiln roller wastes in glazed porcelain tile matte-opaque glaze was investigated. Ground kiln roller waste was used instead of alumina, quartz, and zircon in a standard matte-opaque glaze composition. The developed glazes were sintered at 1190 °C for 44 min. The thermal, optical, and physical properties of the glazes were examined and compared with the standard glaze recipe. The melting behaviors of the glazes were measured with a heating microscope, and the thermal expansion coefficients were measured with a dilatometer. The phases developed in the structure were determined by XRD analysis and scanning electron microscope (SEM). According to the results, the usage of roller waste instead of alumina and quartz decreased the crystal phase development in the glaze and the opacity, causing an increase in surface glossiness. When it was used instead of zircon, anorthite and crystal phase development increased and the surface brightness decreased, but the opacity decreased significantly due to the decline of zircon crystals. Considering all these thermal and optical properties, it was determined that the use of roller waste would be possible with some optimizations in the composition of matte-opaque glaze composition.