A. Low co-efficient of thermal expansion
B. Poor thermal spalling resistance
C. Tendency to expand unduly high during firing
D. Very high cost
Related Mcqs:
- Porosity of fireclay refractories is _______________ percent?
A. 5-10
B. 10-25
C. 25-35
D. 35-50 - Faster rate of drying of moulded refractories results in high _____________ of refractories?
A. Green strength
B. Voids
C. Shrinkage
D. Both B. and C. - Carbon refractories have very high __________________?
A. Wetting characteristics
B. Refractoriness
C. Thermal conductivity
D. Both B. and C. - Furnace atmosphere for softening temperature determination of refractories (in which Seger Cones are placed) should be __________________?
A. Oxidising
B. Neutral
C. Either A. or B.
D. Neither A. nor B. - 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 - Addition of grog in fireclay brick during its manufacture is advantageous, because it results in_____________________?
A. Less shrinkage in heating, decreased apparent porosity & increased specific gravity
B. High strength & thermal spalling resistance
C. Less addition of water to get a workable plasticity & lesser time required for drying the raw
refractories and hence increased rate of production
D. All A., B. and C. - Cold crushing strength of ordinary fireclay brick is about 950 kg/cm2. On exposure to a temperature of about 1500°C, its crushing strength may come down to as low as ______________ kg/cm2?
A. 450
B. 250
C. 150
D. 65 - Colour of fireclay bricks is_________________?
A. Light buff to reddish buff
B. Yellow
C. Black
D. None of these - Fireclay bricks are used in the__________________?
A. Coke ovens regenerator
B. Outer lining of L.D. converter
C. Hearth bottom of blast furnace
D. Coke oven walls - Fireclay bricks are not used in the_____________________?
A. Blast furnace
B. Hot blast stove
C. Cupola
D. Wall of coke oven
