A. Greater diffusivity
B. Low specific heat
C. Low thermal co-efficient of expansion
D. All A., B. and C.
Related Mcqs:
- 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 - Spalling tendency of refractories is reduced by increasing its_________________?
A. Porosity
B. Specific gravity
C. Thermal conductivity
D. Strength - Sillimanite (Al2O3.SiO2) refractory, which is a neutral refractory, is not used in________________?
A. Pottery furnace
B. Glass melting furnace
C. Crucibles
D. Gas retorts - Thermal spalling mainly occurs during _____________ of furnaces?
A. Cooling down
B. Warming up
C. Both A. & B.
D. Neither A. nor B. - With increase in the porosity, thermal spalling resistance of fireclay brick___________________?
A. Increases
B. Decreases
C. Remain same
D. May increase or decrease - 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 - 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 - 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 - Test piece for determination of RUL of a refractory is heated in a/an____________________?
A. Oxidising atmosphere
B. Reducing atmosphere
C. Electric furnace
D. Neutral atmosphere
