Refractory Technology MCQs

Question 1

Slide gates in teeming laddie used for steel pouring in ingot moulds is lined with __________ bricks.

Accepted Answer

Bakelite impregnated or fused periclase

Answer

Silica

Answer

Semi-silica

Answer

Fireclay

Question 2

Graphite or carbon refractories

Accepted Answer

Should be used in neutral or reducing atmosphere

Answer

Exihibit wetting characteristics

Answer

Exhibit high shrinkage on thermal treatment

Answer

Are not resistant to corrosion by slag

Question 3

Refractory materials are never used in the construction of

Accepted Answer

Pressure vessels

Answer

Segar cones

Answer

Orton cones

Answer

Ovens & retorts

Question 4

Skull is not formed on the carbon blocks in the hearth of a blast furnace, when it becomes cold, becaus of its

Accepted Answer

Non-wetting characteristic

Answer

High thermal conductivity

Answer

High crushing strength

Answer

None of these

Question 5

Refractory castables are used for

Accepted Answer

All of the above

Answer

Producing monolithic linings

Answer

Patch work

Answer

Minimising the number of joints in the structure

Question 6

Pick out the wrong statement.

Accepted Answer

Refractories used in muffle furnace should have low thermal conductivity

Answer

The electrical resistivity of refractories drops rapidly with rise in temperature

Answer

For reducing spalling tendency, the refractory should be well fired and its porosity should be more

Answer

Refractoriness under load (RUL) of a refractory is always less than its refractoriness

Question 7

Which is the most stable crystalline form of silica at room temperature?

Accepted Answer

Quartz

Answer

Cristobalite

Answer

Tridymite

Answer

None of these

Question 8

Presence of MgO in alumino-silicate refractories __________ its refractoriness.

Accepted Answer

Lowers

Answer

Increases

Answer

Does not affect

Answer

Either A or B; depends on its quantity

Question 9

Which is not a natural insulating material?

Accepted Answer

None of these

Answer

Diatomaceous earth/kieselgur

Answer

Asbestos

Answer

Vermiculite