Crystallization kinetics and microhardness of MgO-AI_2O_3-SiO_2 glass ceramics with low melting temperature

摘要

The authors report a deferential scanning calorimetric study of MgO-AI_2O_3-SiO_2 glasses which possess low melting temperature due to introduction of some quantity of B2O3, Ii_2O and CaF_2. It is shown that the content of Li_2O has a strong impact on the overlapping extent of the rates of nucleation and crystal growth. High-quartz tends to precipitate at low temperature (—1173 K) for the studied glasses, irrespective of L1_2O content. With increasing annealing temperature, spodumene and cordierite form as main crystalline phase for the samples with high and low L1_2O content, respectively, and then cristobalite crystals occur for both glass compositions. Microhardness firstly increases and then decreases, depending on crystalline phase sequence, and a maximum microhardness value is obtained to be 10.5 GPa.