Related Mcqs:

1. Cermets are combination of ceramic and metallic materials due to which they have high strength & resistance to high temperature. Cermets are used in the_______________?

   A. Hearth of the blast furnace
   B. Nuclear reactors, missiles & space crafts
   C. Insulation of high temperature furnaces
   D. Roof of electric furnaces

2. High thermal conductivity of a refractory material is not important, when it is to be used in the______________________?

   A. Coke oven regenerators
   B. Muffle furnace
   C. Blast furnace
   D. Recuperators

3. Cermets are____________________?

   A. Composite material containing both ceramic & metallic constituents
   B. Having high strength & resistance to high temperature
   C. Used in space vehicles, missiles & nuclear energy plants
   D. All A., B. and C.

4. Ceramic recuperators used for waste heat recovery from high temperature flue gas going out of the furnace is made of________________?

   A. Fireclay
   B. Silicon carbide
   C. Corundum
   D. Siliceous fireclay

5. Thermal conductivity of refractory bricks_________________?

   A. Increases with decrease in porosity
   B. Decreases with decreases in porosity
   C. Is independent of its porosity and is maximum for insulating bricks
   D. Increases with the amount of air entrapped in pores

6. Thermal diffusivity of a refractory brick is high, when its ____________ is high?

   A. Density
   B. Specific heat
   C. Thermal conductivity
   D. None of these

7. Maximum alumina content in high alumina refractory can be as high as _____________ percent?

   A. 30
   B. 50
   C. 70
   D. 90

8. Pure bauxite is the best raw material for the manufacture of high alumina refractories, in which maximum alumina content can be as high as _____________ percent?

   A. 55
   B. 70
   C. 80
   D. 90

9. Maximum shrinkage in volume occurring during burning/firing of dried refractories may be as high as ______________ percent?

   A. 10
   B. 15
   C. 20
   D. 30

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

    A. Increases
    B. Decreases
    C. Remain same
    D. May increase or decrease