Abstract
It is generally mentioned that quartz is stable up to 867°C, that tridymite is the stable polymorph from 867°C to 1470°C, and that cristobalite is the stable phase of silica between 1470°C and the melting point in silica refractories. However it was sometimes found that cristobalite appeared in silica refractories used at the stable temperature region of tridymite in hot blast stove or some other furnaces. The cause of this phenomenon and its transformation mechanism were, therefore, studied.
The transformation temperature of tridymite-cristobalite is also 1470°C in sample used in this research. But when the dust of hot blast stove was added to the sample, an amount of cristobalite increased at 1400°C. It was found that the transformation temperature of tridymite-cristobalite dropped gradually with addition of aluminium oxide. The transformation temperature, however, approached to 1470°C with the increase of calcium oxide in silica refractories.
