Refractory Technology MCQs

Question 1

Tar bonded dolomite bricks

Accepted Answer

All of the above

Answer

Are stored under controlled temperature & humidity to avoid hydration

Answer

Are used in outer lining of L.D. converters

Answer

Have poorer hydration resistance than pitch bonded bricks

Question 2

Which is the stable form of silica below 870°C ?

Accepted Answer

Quartz

Answer

Tridymite

Answer

Cristobalite

Answer

None of these

Question 3

Insulating refractories should have

Accepted Answer

Low thermal conductivity

Answer

High porosity

Answer

Both A & B

Answer

Neither A nor B

Question 4

Most Cermets, which normally have high thermal conductivity and high thermal shock resistance, comprises of ceramic & metallic components of __________ percent respectively.

Accepted Answer

80 and 20

Answer

20 and 80

Answer

50 and 50

Answer

60 and 40

Question 5

silicon carbide refractories have very low

Accepted Answer

None of these

Answer

Refractoriness (< 1700°C)

Answer

Thermal conductivity

Answer

Resistance to thermal shock

Question 6

Which form of silica has the highest specific gravity?

Accepted Answer

Quartz

Answer

Cristobalite

Answer

Tridymite

Answer

All of the above

Question 7

Which of the following bricks should not be used, if the furnace is to be used intermit-tantly?

Accepted Answer

Silica bricks

Answer

Firebricks

Answer

Silicon carbide bricks

Answer

Sillimanite

Question 8

Which is not an acidic refractory?

Accepted Answer

Carbon black

Answer

Silica

Answer

Fireclay

Answer

High alumina refractory