Chemical Engineering - Refractory Technology

36. 

Pick out the wrong statement.

A. A ceramic material which becomes fluid upon heating and can be moulded in liquid/viscous state is termed s glass.
B. Ceramic materials do not undergo vitrification on heating.
C. Ceramic materials are brittle in nature.
D. Non-oxide ceramic materials generally act as a semi-conductor.

Answer: Option B

Explanation:

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37. 

Lower wall courses of soaking pits are made of __________ bricks to avoid the action of molten slag & scale.

A. chrome or magnesite
B. silicon carbide
C. silica
D. lowduty fireclay

Answer: Option A

Explanation:

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38. 

Addition of grog in fireclay brick during its manufacture is advantageous, because it results in

A. less shrinkage in heating, decreased apparent porosity & increased specific gravity.
B. high strength & thermal spalling resistance.
C. less addition of water to get a workable plasticity & lesser time required for drying the raw refractories and hence increased rate of production.
D. all (a), (b) and (c).

Answer: Option D

Explanation:

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39. 

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

A. bakelite impregnated or fused periclase
B. silica
C. semi-silica
D. fireclay

Answer: Option A

Explanation:

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40. 

Fireclay refractories

A. are not resistant to the action of basic slags.
B. combine with salts (e.g. chlorides sulphates etc.) & bases (e.g. lime, magnesia etc.) forming fusible aluminates silicates etc.
C. shrink during firing
D. all (a), (b) and (c)

Answer: Option D

Explanation:

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