CaO-ZrO_2-SiO_2 Glass-Frit Addition to Porcelainized Stoneware: Enhancement of Tiles Colouring Capabilities

摘要

Porcelainized stoneware tiles have experienced many aesthetic improvements in the last few years, occasionally accompanied by some depletion of surface properties. The introduction of 5-10 mass-percent of an easily devitrifiable glass frit leads to a significant increase in the white index of the ceramic body, simultaneously allowing a better exploitation of pastel hues colouring additives in bulk coloured porcelainized stoneware tiles. Optimum sintering temperature, densification, and water absorption of compositions with glass-frit addition are comparable to large-scale production porcelainized stoneware tiles. Moreover, when ceramic tiles are fired according to the typical industrial fast-firing cycle of 60 min up to 1200 deg C, the flexural strength, indicated by the modulus of rupture measured values, benefits from glass-frit addition.