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.