A. Cristobalite
B. Tridymite
C. Quartz
D. None of these
Related Mcqs:
- Which is the stable form of silica upto 1470°C ?
A. Quartz
B. Cristobalite
C. Tridymite
D. None of these - Which is the most stable crystalline form of silica at room temperature ?
A. Quartz
B. Cristobalite
C. Tridymite
D. None of these - Which is the stable form of silica below 870°C ?
A. Tridymite
B. Cristobalite
C. Quartz
D. None of these - Semi-silica bricks compared to silica bricks have_______________?
A. Less fusion point
B. Better spalling resistance
C. Both A. and B.
D. Neither A. not B. - Which form of silica has the highest specific gravity ?
A. Quartz
B. Cristobalite
C. Tridymite
D. All have the same specific gravity - With increase in the density of silica refractories, its_______________?
A. Resistance to slag attack increases
B. Spalling resistance reduces
C. Both A. and B.
D. Neither A. nor B. - Refractoriness of a typical silica brick corresponds to Segar cone number, ’32’, which is equivalent to a temperature of _____________ °C?
A. 1380
B. 1520
C. 1710
D. 1915 - Silica refractories are not used in _________________?
A. Coke oven walls
B. Beehive coke ovens
C. Dome and upper portion of B.F. stoves
D. Open hearth furnace roof - Porosity of silica bricks varies from ______________ percent?
A. 5 to 10
B. 20 to 30
C. 45 to 60
D. 60 to 75 - Silica bricks have low spalling resistance below 600°C, due to its________________?
A. Very high thermal conductivity
B. High co-efficient of expansion upto this temperature
C. High thermal diffusivity
D. Low refractoriness
