Effect of nucleating agents on the crystallization behaviour and microstructure of SiO 2 –CaO–MgO (Na 2 O) glass-ceramics

Abstract The crystallization behaviour of the ternary SiO 2 –MgO–CaO system comprising different nucleating agents was investigated using DTA and XRD techniques. The effect of compositional changes on bulk crystallization and growth morphology were also studied. After a two-stage heat treatment, the phases such as wollastonite, diopside and in some cases, cristobalite, were identified. The microstructures were investigated by SEM. It was found that the pairs of V 2 O 5 +MoO 3 and CaF 2 +MoO 3 are more effective nucleants compared with that of Fe 2 O 3 +WO 3 . The coarse fibrous morphology with directional surface crystallization was observed for some specimens containing Fe 2 O 3 +WO 3 as nucleants