Carbon refractories have very high __________________?

Related Mcqs:

1. Faster rate of drying of moulded refractories results in high _____________ of refractories?

   A. Green strength
   B. Voids
   C. Shrinkage
   D. Both B. and C.

2. 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

3. Carbon refractories are exclusively used in the_________________?

   A. Hearth of blast furnace
   B. Walls of coke oven
   C. Regenerators of coke oven
   D. Side wall of soaking pits

4. 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.

5. Fireclay refractories have __________________?

   A. Low co-efficient of thermal expansion
   B. Poor thermal spalling resistance
   C. Tendency to expand unduly high during firing
   D. Very high cost

6. 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

7. Because of its very high refractoriness of the order of __________ °C, silicon carbide refractories are used in zinc smelting furnace, muffle furnace and for supporting the wares in tunnel kilns ?

   A. 1800
   B. 2200
   C. 2400
   D. 2700

8. High alumina refractories are used in the ___________________?

   A. Dome of blast furnace stoves
   B. Electric arc furnace roof
   C. Glass melting furnaces
   D. All A., B. and C.

9. Si percentage in silica refractories used in the walls of coke oven is about______________________?

   A. 45
   B. 60
   C. 80
   D. 95

10. Magnesite refractories are generally not used in the___________________?

    A. Electric furnace walls
    B. Steel melting furnace
    C. Open hearth furnace
    D. Burning zone of cement kilns