Crystallization behavior and mechanical properties of porcelain bodies containing zinc oxide additions

The effects of ZnO addition on the crystallization behavior and mechanical properties of porcelain bodies have been investigated. When ZnO was incorporated, gahnite (ZnAl2O4) phase crystallized from 1130 °C, after feldspar had significantly melted and ZnO dissolved into the glass. Cristobalite formation was promoted with the addition of ZnO. However, alumina used as a raw material remained almost intact during sintering. An abundance of gahnite crystals with sizes of 50-400 nm were observed inside the glassy phase, which might contribute to the improved mechanical properties of the porcelain bodies. The flexural strength depended more considerably on the amount of ZnO, in comparison with water absorption and sintering temperature. Wear resistance was enhanced with the addition of ZnO.