Glass forming ability and thermal stability of F-phlogopite based glasses
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 fr...
| Autores: | , , |
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| Formato: | artículo |
| Estado: | Versión aceptada para publicación |
| Fecha de publicación: | 2015 |
| País: | España |
| Recursos: | Consejo Superior de Investigaciones Científicas (CSIC) |
| Repositorio: | DIGITAL.CSIC. Repositorio Institucional del CSIC |
| OAI Identifier: | oai:digital.csic.es:10261/129339 |
| Acesso em linha: | http://hdl.handle.net/10261/129339 |
| Access Level: | acceso abierto |
| Palavra-chave: | F-phlogopite DSC Hrubrÿ, Weinberg Lu-Liu glass-forming ability Crystallisation mechanism |
| Resumo: | 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 wt. %, 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 (TTS), reduced glass transition temperature (Tgr), Weinberg (Kw), Hrubÿ (KH) and Lu-Liu (KLL) parameters. The prevalent crystallisation mechanism for each glass was assessed by determining the dissimilarity in crystallisation temperature (Tp) between fine (<63μm powder) and coarse glass samples. The estimation of glass forming ability (GFA) was based on the critical cooling rate (qc), which is determined from the Weinberg, Hrubÿ and Lu-Liu parameters. The results point out that the compositions of these glasses result in melts with a high tendency to crystallize during cooling (qc > 120°C/min) and obtaining amorphous glasses is only possible by fast cooling of the melt. In a subsequent thermal treatment, a volume crystallization 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 (FESEM) and X-ray diffraction (XRD). |
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