The effect of Al2O3 on sintering and crystallization of MgSiO3-based glass-powder compacts

The influence of Al2O3 (8 wt.%) on sintering and crystallization features of glass powders based on magnesium silicate (MgSiO3) was experimentally determined. The investigated compositions were Y0.125Mg0.875Si0.875B0.125O3 and Y0.125Mg0.725Ba0.15Si0.875B0.125O3. For the experiments, glasses in bulk and frit forms were produced by melting in Pt-crucible at 1600 °C for 1.5 h. Glass-powder compacts were sintered at different temperatures between 900 °C and 1100 °C. The evolution of crystalline regime was determined by in situ recording of X-ray diffractograms of fine glass powders at elevated temperatures. The results and their discussion showed that addition of 8 wt.% Al2O3 in glass batches affected the thermal properties of the glasses and resulted in MgSiO3-based glass ceramics well sintered between 900 °C and 1100 °C. In the BaO-free MgSiO3 glass ceramics, clino- and orthoenstatite crystallize while the presence of BaO favours the formation of hexacelsian.