A. High porosity
B. Low thermal conductivity
C. Both A. and B.
D. Neither A. not B.
Related Mcqs:
- Porosity is induced in insulating refractories by adding________________?
A. Powdered naphthalene
B. Ammonium chloride/sulphate
C. Calcium phosphate
D. All A., B. and C. - Faster rate of drying of moulded refractories results in high _____________ of refractories?
A. Green strength
B. Voids
C. Shrinkage
D. Both B. and C. - Semi-silica bricks compared to silica bricks have_______________?
A. Less fusion point
B. Better spalling resistance
C. Both A. and B.
D. Neither A. not B. - Hot face insulating linings of high purity alumina fused mullite are used, where_________________?
A. Very high temperatures are involved
B. Highly reducing conditions are involved
C. Presence of iron or silica is harmful
D. All A., B. and C. - Which is required in an insulating refractory ?
A. High thermal conductivity
B. Low porosity
C. Both A. and B.
D. Neither A. nor B. - Which is not a natural insulating material ?
A. Diatomaceous earth/kieselgur
B. Asbestos
C. Vermiculite
D. None of these - 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 - Machine moulding of dry mixture of refractories requires a pressure of the order of _____________ kg/cm2?
A. 10
B. 100
C. 500
D. 1000 - With increase in the density of silica refractories, its_______________?
A. Resistance to slag attack increases
B. Spalling resistance reduces
C. Both A. and B.
D. Neither A. nor B. - Chemically, mullite refractories is____________________?
A. 3Al2O3.2SiO2
B. Al2O3
C. ZrSO4
D. ThO2
