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.Management Sciences
Category: Refractory Technology
Most Cermets, which normally have high thermal conductivity and high thermal shock resistance, comprises of ceramic & metallic components of ______________ percent respectively?
A. 80 and 20
B. 20 and 80
C. 50 and 50
D. 60 and 40
The highest melting pure oxide (m.p. > 3000°C)is___________________?
A. Thoria
B. Alumina
C. Beryllia
D. Zirconia
Cermets are____________________?
A. Composite material containing both ceramic & metallic constituents
B. Having high strength & resistance to high temperature
C. Used in space vehicles, missiles & nuclear energy plants
D. All A., B. and C.
Maximum alumina content in high alumina refractory can be as high as _____________ percent?
A. 30
B. 50
C. 70
D. 90
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
The main raw material for manufacture of silicon carbide refractories is_________________?
A. Corundum
B. Carborundum
C. Bauxite
D. Periclase
10 to 30% magnesite is added to Chromite to produce chrome-magnesite refractories. Magnesite addition is mainly done to improve the _____________ of Chromite?
A. Spalling resistance
B. Refractoriness
C. Crushing strength
D. Resistance to slag
Pure oxide refractories are generally monocrystalline in nature and are self bonded _______________ bricks are generally used as moderator in nuclear reactors?
A. Beryllia
B. Carborundum
C. Corundum
D. Thoria
Magnesite refractories are generally not used in the___________________?
A. Electric furnace walls
B. Steel melting furnace
C. Open hearth furnace
D. Burning zone of cement kilns
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