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

Related Mcqs:

1. 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

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. Firing of refractory brick is done to __________________?

   A. Dehydrate the dried refractory
   B. Develop stable mineral forms in them
   C. Form ceramic bonds necessary for development of high crushing strength in the finished
   product
   D. All A., B. and C.

4. Addition of zircon to silica refractory brick improves its_____________________?

   A. Crushing strength
   B. Resistance to slag attack
   C. Both A. and B.
   D. Neither A. nor B.

5. Sillimanite (Al2O3.SiO2) refractory, which is a neutral refractory, is not used in________________?

   A. Pottery furnace
   B. Glass melting furnace
   C. Crucibles
   D. Gas retorts

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

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

7. 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

8. High porosity refractory bricks have _______________?

   A. Poor resistance to the penetration of molten slag, metal & flue gases
   B. Poor heat conductivity & low strength
   C. Better thermal spalling resistance
   D. All A., B. and C.

9. Which of the following is not a high alumina refractory material ?

   A. Kyanite
   B. Sillimanite
   C. Diaspore
   D. Periclase

10. High alumina refractory compared to fireclay bricks have____________________?

    A. Less load bearing capacity
    B. Less resistance to slag attack
    C. Low refractoriness
    D. High resistance to thermal shock and creep