Effect of Fluxing Additives in Iron-rich Frits and Glazes in the Fe2O3–SiO2–CaO–Al2O3 System

Abstract

Glasses in the Fe2O3–SiO2–CaO system are potential candidates for many technological applications due to their ferrimagnetic and semiconductive properties, which have been extensively studied; in this sense, the effect of adding different melting additives like Li2O, B2O3, in this glass system on frits and glazes with 30–40 mass-% of Fe2O3 was studied. Ceramic frits were melted at different temperatures with subsequent cooling in water. Samples were characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD), scanning electron microscopy (SEM), differential thermal analysis and thermogravimetry (DTA, TG) and by heating microscopy. Finally, frits were applied as glazes on ceramic tiles to evaluate their capacity to adapt to the tile productive process. The frits showed low to high homogeneity (depending on the fusion temperature) and oxidation phenomena. High temperature fusion led to the crystallization of magnetite during cooling. Glaze porosity was observed after heat treatment with the presence of anorthite and hematite as crystalline phases in glazes.