Refractory Technology MCQs

Question 1

Silica bricks have low spalling resistance below 600°C, due to its

Accepted Answer

High co-efficient of expansion upto this temperature

Answer

Very high thermal conductivity

Answer

High thermal diffusivity

Answer

Low refractoriness

Question 2

Refractories subjected to alternate cycles of heating & cooling are liable to loose their resistance to

Accepted Answer

Thermal spalling

Answer

Slag attack

Answer

Fusion under load

Answer

CO attack

Question 3

Lower part of hot metal mixer are lined with __________ bricks.

Accepted Answer

Carborundum

Answer

Superduty fireclay

Answer

High alumina

Answer

Silica

Question 4

Which is not an alumino-silicate refractory?

Accepted Answer

Tar dolomite bricks

Answer

Fireclay bricks

Answer

Mullite bricks

Answer

High alumina bricks

Question 5

__________ is the measure of the strength of refractory under the combined effect of temperature & load.

Accepted Answer

RUL

Answer

Porosity

Answer

Specific gravity

Answer

Thermal conductivity

Question 6

Spalling of silica bricks occurs due to abrupt volume changes, when it is cooled below a temperature of __________ °C.

Accepted Answer

270

Answer

770

Answer

570

Answer

70

Question 7

Hot blast main (carrying air at 1000°C) in blast furnace are lined with __________ bricks.

Accepted Answer

Fireclay

Answer

Silica

Answer

Magnesite

Answer

Zirconia

Question 8

Which one expands on heating?

Accepted Answer

Silica bricks

Answer

Fireclay bricks

Answer

Both A & B

Answer

Neither A nor B

Question 9

Pick out the wrong statement.

Accepted Answer

Carbon refractories can not be used in the furnaces operating under reducing conditions

Answer

Sand & coke is the main raw material for the manufacture of silicon carbide

Answer

Mullite can be obtained by the heating of alusite, kyanite or silimanite

Answer

Silica occurs in nature in all cellular, amorphous or crystalline form