Category: Refractory Technology

A. Electrical conductivity of refractory is not important, when these are to be used in electrical
furnaces
B. Graphite and metals are the good electrical conductor among the refractories and others are all
electrical insulators
C. Refractories used for lining electrical furnaces should ordinarily have very low electrical
conductivity
D. Electrical conductivity of porous refractory material is low

A. CaO
B. MgO
C. Al2O3
D. SiO2

A. Tar dolomite
B. Carbon
C. Silica
D. Fireclay

A. Stable form of silica upto 870°C
B. Converted to Tridymite on firing between 870 to 1470°C
C. Transformed to Cristobalite on heating above 1470°C
D. All A., B. and C.

A. Mullite
B. Corundum
C. Bauxite
D. Dolomite

A. Do not burn/oxidise, when exposed to air on heating
B. Are not attacked by slags, as they are not wetted by melts
C. Do not resist temperature fluctuations
D. Have extremely low thermal & electrical conductivities

A. Quartz
B. Cristobalite
C. Tridymite
D. None of these

A. Acidic in nature
B. Neutral in nature
C. Having higher RUL than silica bricks
D. Made by mixing 30% Chromite and 70% Periclase