Category: Refractory Technology

A. Crystalline form of MgO
B. MgCO3
C. ZrSO4
D. Amorphous magnesite

A. Silica bricks
B. Fireclay bricks
C. Both A. & B.
D. Neither A. nor B.

A. High spalling resistance
B. Low spalling resistance
C. High resistance to fusion
D. Low porosity

A. 0
B. <1
C. 1
D. >1

A. Strength
B. Thermal conductivity
C. Spalling resistance
D. None of these

A. Greater diffusivity
B. Low specific heat
C. Low thermal co-efficient of expansion
D. All A., B. and C.

A. Washing action of metal
B. Corrosion by layer of slag
C. Both A. & B.
D. Neither A. nor B.

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.

A. Fluxing material like lime is added in clay to reduce the vitrification temperature
B. Main constituents of clay are alumina and silica
C. Addition of sand in ceramic materials makes it non-plastic, increases its fusion point and
reduces its shrinkage on burning
D. Vitrification of fireclay material is done to increase its porosity

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