Study of the sol-gel processing of glass-ceramic powders in the SiO_2-Al_2O_3-CaO-CaF_2 system. Part 2: microstructure evaluation

摘要

As an effort to develop high purity, homogeneous glasses and glass-ceramic powders in the SiO_2 -Al_2O_3 -CaO -CaF_2 system with controlled microstructures, the present work aimed at the microstructure evaluation of such powders obtained by the sol-gel technique through X-ray diffraction analysis and differential thermal analysis. According to the fluorine/calcium ratio, it was possible to obtain glass-ceramics with one or more of the following phases: fluorite, anorthite, t-mullite and a mixture of calcium fluorosilicates. Changes in the aluminium and silicon contents resulted in glass-ceramics with varying degrees of crystallinity.