Composition dependence of microstructures formed by phase separation in multi-component silicate glass

Abstract

It has been investigated that the correlation between the phase separation and glass compositions in the SiO2-CaO-MgO-Na2O quaternary oxide glasses. The metastable miscibility gap and the spinodal region in the quaternary system have been evaluated from Gibbs energies in the metastable liquid phase, on the assumption that the glass in slag systems could be regarded as a super-cooled liquid. The microstructures corresponding to the phase separation in the glasses have been observed using transmission electron microscopy (TEM). Thermodynamic analyses and the experimental studies revealed the existence of a metastable phase separation including spinodal decomposition in the SiO2-CaO-MgO-Na2O system. Furthermore, it was found that the size of the decomposed microstructure depended on molar ratio of CaO to MgO in the initial glass composition. © 2008 ISIJ.