Glass-forming ability and thermal stability of F-phlogopite-based glasses

Abstract

Listen

Translate article

This paper presents the results of a study that analyses the effect of fluorine content on glass-forming ability (GFA), glass stability (GS) and preferred crystallisation mechanism for a series of glasses in the SiO2–Al2O3–MgO–K2O–F system. Three glass compositions, with fluorine contents ranging from 4.50 to 5.70 mass%, were investigated by differential scanning calorimetry (DSC). The GS was established by estimating different parameters derived from characteristic temperatures of non-isothermal DSC curves, namely, the working range (ΔTTS), reduced glass transition temperature (Tgr), Weinberg (Kw), Hruby (KH) and Lu-Liu (KLL) parameters. The prevalent crystallisation mechanism for each glass was assessed by determining the dissimilarity in crystallisation temperature (ΔTp) between fine ( 120 °C min−1) and obtaining amorphous glasses is only possible by fast cooling of the melt. In a subsequent thermal treatment, a volume crystallisation mechanism will be prevalent in the process of devitrification of these F-phlogopite-based glasses. Nevertheless, the increasing on the fluorine content in the glass composition leads to a variation in the location of the first developed crystals from the internal volume of the glass particle to surface sites. The results established by DSC analyses are verified by the results obtained from field emission scanning electron microscopy and X-ray diffraction.