Related Questions

Porosity of fireclay refractories is __________ percent.
A 5-10
B 10-25
C 25-35
D 35-50
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 of the above
Faster rate of drying of moulded refractories results in high __________ of refractories.
A Green strength
B Voids
C Shrinkage
D Both B and C
High alumina refractory compared to fireclay bricks have
A Less load bearing capacity
B Less resistance to slag attack
C Low refractoriness
D High resistance to thermal shock and creep
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 of the above
Maximum safe working temperature for fireclay bricks is about __________ °C.
A 1150
B 1300
C 1450
D 1550
Fireclay bricks is not used for lining the
A Cupola
B Gas producer
C Bottom of hot metal mixer
D Roof of open hearth furnace
Colour of fireclay bricks is
A Light buff to reddish buff
B Yellow
C Black
D None of these
With increase in the porosity, thermal spalling resistance of fireclay brick
A increases
B decreases
C remains same
D may increase or decrease
Grog addition in fireclay during brick manufacture is done to
A Reduce its shrinkage on heating
B Impart greater spalling resistance
C Enhance the strength of fired refractories
D All of the above

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