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.Management Sciences
Category: Refractory Technology
Cold crushing strength of fireclay bricks is about ______________ kgf/cm2?
A. 50-100
B. 100-150
C. 200-400
D. 500-1000
___________________ is the measure of the strength of refractory under the combined effect of temperature & load ?
A. Porosity
B. RUL
C. Specific gravity
D. Thermal conductivity
Refractory materials are never used in the construction of _________________?
A. Segar cones
B. Orton cones
C. Pressure vessels
D. Ovens & retorts
Fireclay bricks are not used in the _________________?
A. Beehive coke oven
B. By-product coke oven walls
C. Combustion chamber of B.F. stoves
D. Coke oven regenerators
Carbon refractory blocks ___________________?
A. Are wetted by molten iron
B. Are used in the hearth of blast furnace
C. Are acidic in nature
D. All A., B. and C.
Beryllia (which is used in making crucibles for melting uranium & thorium) is superior to alumina in all respects for high temperature (> 1900°C ) use, except ?
A. Cost
B. Electrical conductivity
C. Thermal conductivity
D. Fusion point
With increase in the alumina content, the refractoriness of high alumina refractories_______________?
A. Increases
B. Decreases
C. Remain same
D. May increase or decrease
Which of the following has the lowest electrical resistivity ?
A. Graphite
B. Fireclay
C. Alumina
D. Zircon
Spalling of a refractory means its____________________?
A. Softening
B. Fracture due to uneven expansion at high temperature
C. Resistance to compressive loads
D. Resistance to chemical action of gases and molten fluxes
Faster rate of drying of moulded refractories results in high _____________ of refractories?
A. Green strength
B. Voids
C. Shrinkage
D. Both B. and C.
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