Crystallisation and microstructure of nepheline–forsterite glass-ceramics

This work presents the results of a study focused on the development of forsterite–nepheline glass-ceramic with the use of rice husk ash (RHA) as a silica source. The glass-ceramics were produced by a sintering process of a glassy frit formulated in the MgO–Al2O3–SiO2 base system with the addition of B2O3 and Na2O to facilitate the melting and pouring processes. The crystallisation study was carried out by depicting the TTT curve (Time–Temperature–Transformation). The mineralogical characterisation of the glass-ceramic materials was carried out using the X-ray diffraction (XRD). The crystallisation activation energies were calculated by the Kissinger method. The results obtained show that devitrification of the RHA glass leads to a glass-ceramic material composed of nepheline (Na2O·Al2O3·2SiO2) and forsterite (2MgO·SiO2). A study of the microstructure by scanning electron microscopy (SEM) allowed to establish the morphological evolution in both the shape and spatial arrangement of the nepheline and forsterite crystals on heating.