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 ?

Related Mcqs:

1. Silicon carbide refractories have very low ___________________?

   A. Refractoriness (< 1700°C)
   B. Thermal conductivity
   C. Resistance to thermal shock
   D. None of these

2. Silicon carbide refractories are used in the _____________?

   A. Muffle furnace
   B. Zinc smelting furnace
   C. Ceramic recuperators
   D. All A., B. and C.

3. The main raw material for manufacture of silicon carbide refractories is_________________?

   A. Corundum
   B. Carborundum
   C. Bauxite
   D. Periclase

4. Presence of MgO in alumino-silicate refractories _______________ its refractoriness?

   A. Increases
   B. Lowers
   C. Does not affect
   D. Either A. or B.; depends on its quantity

5. Refractoriness/fusion points of ‘Superduty’ refractories is _______________ °C?

   A. 1520-1630
   B. 1630-1670
   C. > 1730
   D. > 2000

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

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

7. With increase in the alumina content, the refractoriness of high alumina refractories_______________?

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

8. High refractoriness of refractory bricks means, that it has a________________?

   A. High spalling resistance
   B. Low spalling resistance
   C. High resistance to fusion
   D. Low porosity

9. 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

10. Rotary kilns meant for calcination of limestone are lined with chrome magnesite in ______________ zone?

    A. Preheating
    B. Cooling
    C. Burning
    D. All the above