PRODUCTION PROCESS AND SERVICE OF QUARTZ STEEL-CASTING REFRACTORIES. PT.2. SOME PROPERTIES AND SPECIAL FEATURES OF SERVICE

The influence of material purity and method of preparation on the performance of fused silica refractories in the steel industry is discussed. Quartz which has been fused to transparency, containing in excess of 99.7% SiO2, sinters to high density without crystallisation, whereas in refractories fabricated using non-transparent silica glass containing less than 99.5% SiO2 readily converts to cristobalite during firing, even when temperatures as low as 1200-1250 C are employed, resulting in low density. Refractories manufactured using fused silica of low cristobalite content prepared using a low-temperature plasma are described, particularly nozzles for steel casting. The nozzles are suitable for use with steels containing up to 0.8-1.0% Mn, the service life depending upon porosity, microstructure, and pore structure. 5 refs.