Processability, crystallization and mechanical strength of P₂O₅-modified glasses and glass-ceramics in the system MgO-Al₂O₃-SiO₂-TiO₂

Abstract

The crystallization behaviour and the processability of P₂O₅-modified glasses in the MgO-Al₂O₃-SiO₂-TiO₂ system were investigated. The hot-press furnace system "Empress IPS 500" was used to estimate the processability of the glasses. The crystallization process of the glasses was changed with increasing P₂O₅ content. The stability range of the α-quartz solid solution crystal phase decreases and cristobalite becomes the main crystalline phase in glass-ceramics with high P₂O₅ amounts. Magnesium orthophosphate was detected as a phosphorus-containing crystal phase. Glass-ceramics with high mechanical strength crystallize from these modified glasses. The investigations show that the high mechanical strength of the glass-ceramics is related to the crystallization of crystal phases with a high coefficient of thermal expansion.