| Glasses of the composition 2MgO·2Al2O 3·5SiO2 were successfully nucleated with additions of up to 8 mol% TiO2 to form fully crystalline glass-ceramic bodies. The predominant crystalline phase is a hexagonal stuffed quartz structure when the glasses are heated to temperatures near 950°C. This phase transforms to the hexagonal indialite phase at higher temperatures. The nucleating effect of the TiO2 addition results in a fine grained glass-ceramic. Both the glass transition temperature (Tg) and the melting temperature (Tm) decreased with a linear dependence on the amount of TiO 2 added to the glass. Glass of the composition 2MgO·2Al 2O3·5SiO2 + 8 mol% TiO2 was ground and air plasma sprayed onto low thermal expansion castable refractory concretes as a glaze. This glaze remained intact on the refractory concretes during crystallization. This behavior was observed during and after limited thermal cycling of the glazed refractory concretes, and also after high temperature heat treatment of the glazed refractory concretes. |
