A. Cooling down
B. Warming up
C. Both A. & B.
D. Neither A. nor B.
Related Mcqs:
- With increase in the porosity, thermal spalling resistance of fireclay brick___________________?
A. Increases
B. Decreases
C. Remain same
D. May increase or decrease - 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 - Spalling resistance of a refractory cannot be increased by ____________________?
A. Increasing its porosity
B. Using a coarser grog during its manufacture
C. Decreasing its thermal co-efficient of expansion
D. Making it denser - To resist spalling tendency, a refractory should have________________?
A. Greater diffusivity
B. Low specific heat
C. Low thermal co-efficient of expansion
D. All A., B. and C. - 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 - Spalling tendency of refractories is reduced by increasing its_________________?
A. Porosity
B. Specific gravity
C. Thermal conductivity
D. Strength - In panel test for spalling resistance, the average face temperature of panel assembly is maintained at ______________ °C for 24 hours?
A. 700
B. 1000
C. 1600
D. 2000 - 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 - Magnesite bricks are used in those parts of furnaces, which are __________________?
A. Subjected to temperature fluctuation
B. Required to resist corrosive basic slag
C. Subjected to high load
D. None of these - Walls, roofs & combustion chambers of annealing furnaces are made of ______________ bricks?
A. High duty fireclay
B. Silica
C. Mullite
D. Carborundum
