Glass-forming ability and thermal stability of F-phlogopite-based glasses
- 141 Downloads
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 (ΔT TS), reduced glass transition temperature (T gr), Weinberg (K w), Hrubÿ (K H) and Lu-Liu (K LL) parameters. The prevalent crystallisation mechanism for each glass was assessed by determining the dissimilarity in crystallisation temperature (ΔT p) between fine (<63 µm powder) and coarse glass samples. The estimation of GFA was based on the critical cooling rate (q c), 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 crystallise during cooling (q c > 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.
KeywordsF-phlogopite DSC Hrubÿ, Weinberg Lu-Liu Glass-forming ability Crystallisation mechanism
The authors would like to acknowledge Mrs. P. Díaz for her technical support in the experimental study. R. Casasola and J. M. Pérez express their gratitude to the Spanish National Research Council (CSIC) for their contract through the JAE Program (JAEPre-08-00456 and JAEDoc-08-00362, respectively), which is co-financed by the European Social Fund. The financial support through the projects MAT 2006-05977 and MAT2013-40477-P is also recognised.
- 1.Deer WA, Howie RA, Zussman J. An introduction to rock-forming minerals. 2nd ed. London: Pearson Education Ltd.; 1996.Google Scholar
- 22.Thakur RL, Thiagarajan S. Cent Glass Ceram Res Inst Bull. 1966;13:33.Google Scholar
- 25.Weinberg MC. Phys Chem Glasses. 1994;35:119.Google Scholar
- 31.Davies HA. Phys Chem Glasses. 1976;17:159.Google Scholar
- 32.Lewis MH. Glasses and glass–ceramics, Chapter 3. London: Chapman and Hall; 1989.Google Scholar
- 34.Zanotto ED, Weinberg MC. Phys Chem Glasses. 1989;30:186.Google Scholar
- 40.Maiti PK, Mallik A, Basumajumdar A, Kundu P. Ceram Int. 2010;35:301.Google Scholar
- 41.Omar AA, Hamzawy EMA, Farag MM. Ceram Int. 2009;36:115.Google Scholar
- 43.Brauer DS, Hill RG, O’Donnell MD. Phys Chem Glasses Eur J Glass Sci Technol B. 2012;53:27.Google Scholar