SiO2 (Silicon Dioxide, Silica)

Notas

Silicon dioxide, or silica (SiO2), serves as the foundational glass-forming oxide in ceramic glazes, typically constituting over 60% of most formulations. While naturally abundant as quartz in clay bodies—where it often functions as an inert aggregate—its role in glaze chemistry is to act as a structural building block that integrates with other oxides to create a vitreous matrix. Silica is inherently refractory, requiring the presence of fluxes to achieve a melt; consequently, the ratio of silica to these fluxes dictates the glaze's melting range and fluidity. Its performance is heavily influenced by its ratio with alumina, which governs the glaze's surface finish, with higher silica-to-alumina proportions generally promoting gloss. When formulated alongside boron and alumina, silica contributes to a low thermal expansion, which is essential for minimizing crazing and improving durability, hardness, and chemical resistance. Increasing silica content generally enhances surface brilliance and hardness but also raises the melting temperature and the risk of devitrification. Conversely, reducing silica levels increases melt fluidity. Due to its role in chemical stability, maximizing silica content is a common strategy to improve leaching resistance and strengthen the bond between the glaze and the ceramic body.