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.Management Sciences
Category: Refractory Technology
Which of the following has the lowest electrical resistivity ?
0
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.
Cold crushing strength of refractories depends upon its_________________?
A. Composition
B. Texture
C. Firing temperature
D. All A., B. and C.
Conversion of silica mineral to Cristobalite is accompanied by reduction in its ____________________?
A. Volume
B. Specific gravity
C. Both A. & B.
D. Neither A. nor B.
Fusion point of a basic refractory material is__________________?
A. Reduced by the addition of acid oxides
B. Increased by the addition of acid oxides
C. Not affected by the addition of acid oxides
D. Always less than 1000°C
_____________ nozzles are used in continuous casting of steel?
A. Zircon
B. Thoria
C. Carborundum
D. Beryllia
Which of the following is not a high alumina refractory material ?
A. Kyanite
B. Sillimanite
C. Diaspore
D. Periclase
Vacuum steel degassing units are lined with__________________?
A. Silica bricks
B. Low duty firebricks
C. High alumina bricks
D. Graphite blocks
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