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.Management Sciences
Category: Refractory Technology
Alumina-graphite bricks are used for lining the ____________________?
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A. Slide gate in teeming laddies
B. Continuous casting systems
C. Both A. and B.
D. Neither A. nor B.
Presence of MgO in alumino-silicate refractories _______________ its refractoriness?
A. Increases
B. Lowers
C. Does not affect
D. Either A. or B.; depends on its quantity
Roof of a basic electric furnace is made of _____________ bricks?
A. Superduty fireclay
B. Silica
C. Chromite
D. None of these
Cold crushing strength of a refractory does not depend upon its ____________________?
A. Shape
B. Composition
C. Firing temperature
D. Texture
Maximum water percentage in refractory mix meant for hand moulding may be as high as _____________ percent?
A. 2-3
B. 5-7
C. 7-12
D. 14-20
Fireclay bricks are used in the___________________?
A. Furnaces allowed to cool frequently
B. Flues
C. Chimney linings
D. All A., B. and C.
Which is the most stable crystalline form of silica at room temperature ?
A. Quartz
B. Cristobalite
C. Tridymite
D. None of these
______________ bricks are used in the burning zone of a cement rotary kiln ?
A. High alumina
B. Fireclay
C. Thoria
D. Silicon carbide
Thoria is an expensive refractory material and is radioactive in nature. Thorium oxide is used in the manufacture of______________?
A. Segar cones
B. Muffles for muffle furnaces
C. Insulating bricks
D. Crucibles used for melting of high purity metals
Refractory bricks having lower porosity have_________________________?
A. High insulating properties
B. Low heat capacity
C. Low thermal conductivity
D. Greater strength
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