Except _____________, all other refractories are bad conductors of electricity (i.e, have low electrical conductivity)?

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. Silicon carbide refractories have very low ___________________?

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

3. Magnesite refractories have low resistance to___________________?

   A. Attack by basic slag
   B. Abrasion
   C. Disintegration on sudden change of temperature
   D. Both B. and C.

4. Machine moulding of dry mixture of refractories requires a pressure of the order of _____________ kg/cm2?

   A. 10
   B. 100
   C. 500
   D. 1000

5. Silicon carbide refractories are used in the _____________?

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

6. Pyrometric cone equivalent (PCE) value (Segar cone) of ‘Superduty refractories’ is more than 33 which corresponds to a temperature of _____________ °C?

   A. 1520
   B. 1630
   C. 1670
   D. 1730

7. Panel test determines the _____________ of refractories?

   A. Fusion point
   B. Spalling resistance
   C. Slag penetration resistance
   D. Refractoriness under load (RUL)

8. 10 to 30% magnesite is added to Chromite to produce chrome-magnesite refractories. Magnesite addition is mainly done to improve the _____________ of Chromite?

   A. Spalling resistance
   B. Refractoriness
   C. Crushing strength
   D. Resistance to slag

9. Spray test determines the _____________ of refractories?

   A. Resistance to slag penetration
   B. Resistance to CO attack
   C. RUL
   D. Permanent linear change

10. 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