With decrease in porosity, the ______________ of the refractories decreases?

Related Mcqs:

1. Porosity is induced in insulating refractories by adding________________?

   A. Powdered naphthalene
   B. Ammonium chloride/sulphate
   C. Calcium phosphate
   D. All A., B. and C.

2. Porosity of fireclay refractories is _______________ percent?

   A. 5-10
   B. 10-25
   C. 25-35
   D. 35-50

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

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

4. Porosity of silica bricks varies from ______________ percent?

   A. 5 to 10
   B. 20 to 30
   C. 45 to 60
   D. 60 to 75

5. 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

6. Dilatometer is used for the determination of ______________ of refractories?

   A. Modulus of rupture
   B. Permanent linear change
   C. Resistance to CO attack
   D. RUL

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

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

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. Maximum apparent porosity of magnesite bricks is about _____________ percent?

   A. 8
   B. 24
   C. 44
   D. 58

10. Refractory bricks having lower porosity have_________________________?

    A. High insulating properties
    B. Low heat capacity
    C. Low thermal conductivity
    D. Greater strength