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.Management Sciences
Category: Refractory Technology
Refractory castables are used for__________________?
A. Producing monolithic linings
B. Patch work
C. Minimising the number of joints in the structure
D. All A., B. and C.
Fireclay refractories____________________?
A. Are not resistant to the action of basic slags
B. Combine with salts (e.g. chlorides sulphates etc.) & bases (e.g. lime, magnesia etc.) forming
fusible aluminates silicates etc
C. Shrink during firing
D. All A., B. and C.
Which is required in an insulating refractory ?
A. High thermal conductivity
B. Low porosity
C. Both A. and B.
D. Neither A. nor B.
Which form of silica has the highest specific gravity ?
A. Quartz
B. Cristobalite
C. Tridymite
D. All have the same specific gravity
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.
Except _____________, all other refractories are bad conductors of electricity (i.e, have low electrical conductivity)?
A. Fireclay
B. Carborundum
C. Graphite
D. Chromite
Magnesite chrome bricks are used in the___________________?
A. Roof lining of basic open hearth & other basic furnaces
B. Reheating furnaces
C. Soaking pits
D. All A., B. and C.
Magnesite chrome refractories____________________?
A. Have better spalling resistance than chrome magnesite refractories
B. Have very low thermal co-efficient of expansion
C. Are not at all resistant to the corrosive action of iron oxide
D. Have very low (50 kg/cm2) cold crushing strength (C.C.S.), and cannot be used in metalcase
form
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