A. crack when subjected to sudden change of temperature
B. Cannot be used in the dome of hot blast stoves
C. Have lower thermal conductivity than fireclay bricks
D. All A., B. and C.
Related Mcqs:
- 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. - With increasing alumina content, the fusion point of high alumina refractories__________________?
A. Increases
B. Decreases
C. Remain constant
D. May increase or decrease; depends on its alumina content - Which is the most stable crystalline form of silica at room temperature ?
A. Quartz
B. Cristobalite
C. Tridymite
D. None of these - An indication of degree of firing in silica brick is its____________________?
A. Specific gravity
B. Fusion point
C. RUL
D. None of these - 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 - Use of higher percentage of lime for bonding silica bricks, reduces their__________________?
A. Strength
B. Abrasion resistance
C. Both A. & B.
D. Neither A. nor B. - Which is the stable form of silica between 1470°C and the melting point 1713°C ?
A. Cristobalite
B. Tridymite
C. Quartz
D. None of these - Which form of silica has the highest specific gravity ?
A. Quartz
B. Cristobalite
C. Tridymite
D. All have the same specific gravity
