A. High thermal conductivity
B. Low porosity
C. Both A. and B.
D. Neither A. nor B.
Related Mcqs:
- 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 - Porosity is induced in insulating refractories by adding________________?
A. Powdered naphthalene
B. Ammonium chloride/sulphate
C. Calcium phosphate
D. All A., B. and C. - Insulating refractories should have_______________?
A. High porosity
B. Low thermal conductivity
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 not a natural insulating material ?
A. Diatomaceous earth/kieselgur
B. Asbestos
C. Vermiculite
D. None of these - Refractory castables are used for__________________?
A. Producing monolithic linings
B. Patch work
C. Minimising the number of joints in the structure
D. All A., B. and C. - An ideal refractory should have high__________________?
A. Spalling rate
B. Fusion point
C. Shrinkage ability
D. None of these - _____________ is not a single oxide-refractory?
A. Zirconia
B. Silicon carbide
C. Magnesia
D. None of these - 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 - Thoria is an expensive refractory material and is radioactive in nature. Thorium oxide is used in the manufacture of______________?
A. Segar cones
B. Muffles for muffle furnaces
C. Insulating bricks
D. Crucibles used for melting of high purity metals
