Refractory Technology MCQs

Question 1

Firing temperature of magnesite bricks is about __________ °C.

Accepted Answer

1600-1800

Answer

800-1000

Answer

1000-1200

Answer

2400-2600

Question 2

Carbon refractories

Accepted Answer

Are not attacked by slags, as they are not wetted by melts

Answer

Do not burn/oxidise, when exposed to air on heating

Answer

Do not resist temperature fluctuations

Answer

Have extremely low thermal & electrical conductivities

Question 3

With increase in the density of silica refractories, its

Accepted Answer

Both A & B

Answer

Resistance to slag attack increases

Answer

Spalling resistance reduces

Answer

Neither A nor B

Question 4

Which is not a high alumina refractory?

Accepted Answer

Dolomite

Answer

Mullite

Answer

Corrundum

Answer

Bauxite

Question 5

Carbon refractory blocks

Accepted Answer

Are used in the hearth of blast furnace

Answer

Are wetted by molten iron

Answer

Are acidic in nature

Answer

All of the above

Question 6

Hollow refractory bricks are made by

Accepted Answer

Slip casting

Answer

Hand moulding

Answer

Pressing/machine moulding

Answer

Extrusion

Question 7

Carborundum used for making crucibles for melting non-ferrous metals is chemically

Accepted Answer

Silicon carbide

Answer

Silicon nitride

Answer

Crystalline magnesia

Answer

Zirconium sulphate

Question 8

Thermal conductivity of refractory bricks

Accepted Answer

Increases with decrease in porosity

Answer

Decreases with decreases in porosity

Answer

Is independent of its porosity and is maximum for insulating bricks

Answer

Increases with the amount of air entrapped in pores

Question 9

Chrome magnesite bricks are

Accepted Answer

Having higher RUL than silica bricks

Answer

Acidic in nature

Answer

Neutral in nature

Answer

Made by mixing 30% chromite and 70% periclase