CRYSTALLISATION SEQUENCE

IN THE GLASS SYSTEM SiO2 -P2 O5-Al2O3-MgO-Na2O

T. Aboud

Department of Materials and Metallurgical Engineering

AL-Fateh University, Faculty of Engineering

P. O. Box 13579, Tripoli, Libya

* Corresponding author. E-mail : t_aboud@hotmail.com

Received : 08 May 2002; revised version accepted :27 December 2002

Abstract

Differential scanning calorimetry (DSC) thermomechanical analysis (TMA) and Fourier transform infrared spectroscopy (FT-IR) were employed to characterise the obtained SiO2-P2O5-Al2O3-MgO-Na2O glass on the laboratory scale. The sequential crystallisation behavior was investigated using x-ray diffraction (XRD) and scanning electron microscopy (SEM) in conjunction with energy dispersive x-ray analysis (EDX).

It was revealed that the obtained glass has a relatively high thermal stability (poor crystallisation tendency) and crystallisation could only take place after long exposure periods at high temperatures. After 44 hrs. of heating in a well controlled gradient temperature furnace, cordierite and indialite are the main crystallising phases in the temperature range 850-1000oC as confirmed by x-ray diffraction, while corundum and spinel are the major phases to crystallise in the liquid phase at 1000-1100oC with different morphologies. The existence of the latter two phases is confirmed through both x-ray diffraction and scanning electron microscopy.

Keywords: Glasses; Multicomponent; Mixed-network; Indialite; Cordierite; Mullite; Corundum; Spinel; Ceramisation.

 

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