Effect of fluoride nucleating catalysts on crystallization of cordierite from modified basalt-based glasses

Cordierite-anorthite phases were crystallized from modified basalt-based glasses by adding calculated amounts of reducing agent, TiO2, kaolin and F− ions in the form of Li, Mg and Al fluorides as nucleated agents. DTA, XRD and SEM were performed to study the crystallization of these glasses. It was noticed that, AlF3 greatly encourage the formation of anorthite and has an opposite effect on spinel crystallization. The presence of MgF2 decreases the onset of crystallization and enhance cordierite polymorphs and anorthite while LiF stimulates the crystallization of anorthite, β-quartz solid solutions (ss) and minor spinel. Sequence of crystallization is dependent on heat treatment parameters and type of fluorides added.