Processing of glass-ceramics in the SiO_2-Al_2O_3-B_2O_3MgO-CaO-Na_2O-(P_2O_5)-F system via sintering and crystallization of glass powder compacts

摘要

Glass-ceramics were produced by crystallization of glasses in the SiO_2-Al_2O_3-B_2O_3MgO-CaO-Na_2O-F system. The experimental results showed that bulk glasses are prone to surface crystallization. Hence, crystallization of bulk glasses resulted in non-homogeneous crystalline materials, which comprised relatively coarse crystals. Therefore, processing was realized using glass-powder compacts. Maximum densification was reached at 700-750 deg C. This interval is positioned at relatively lower temperatures than those often reported for similar sintered glass-ceramics. Doping with P_2O_5 improved sintering behaviour and broadened sintering temperature range. Sintering between 750 and 800 deg C resulted in materials, which exhibited dense crystalline microstructure and the maximum flexural strength.