With increase in the porosity, thermal spalling resistance of fireclay brick___________________?

Related Mcqs:

1. Porosity of fireclay refractories is _______________ percent?

   A. 5-10
   B. 10-25
   C. 25-35
   D. 35-50

2. Thermal spalling mainly occurs during _____________ of furnaces?

   A. Cooling down
   B. Warming up
   C. Both A. & B.
   D. Neither A. nor B.

3. 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

4. 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

5. 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

6. 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

7. 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

8. 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.

9. Spalling tendency of refractories is reduced by increasing its_________________?

   A. Porosity
   B. Specific gravity
   C. Thermal conductivity
   D. Strength

10. Cold crushing strength of fireclay bricks is about ______________ kgf/cm2?

    A. 50-100
    B. 100-150
    C. 200-400
    D. 500-1000