Related Questions

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
Fireclay refractories have
A Low co-efficient of thermal expansion
B Poor thermal spalling resistance
C Tendency to expand unduly high during firing
D Very high cost
Faster rate of drying of moulded refractories results in high __________ of refractories.
A Green strength
B Voids
C Shrinkage
D Both B and C
With increase in the porosity, thermal spalling resistance of fireclay brick
A increases
B decreases
C remains same
D may increase or decrease
With decrease in porosity, the __________ of the refractories decreases.
A Strength
B Thermal conductivity
C Spalling resistance
D None of these
Porosity is induced in insulating refractories by adding
A Powdered naphthalene
B Ammonium chloride/sulphate
C Calcium phosphate
D All of the above
An insulating refractory brick should have high porosity and low thermal conductivity. Which of the following is not used for inducing porosity in the insulating refractory bricks during its manufacture?
A Cork
B Saw dust
C Sand
D Chemically prepared foam
Maximum safe working temperature for fireclay bricks is about __________ °C.
A 1150
B 1300
C 1450
D 1550
Pure bauxite is the best raw material for the manufacture of high alumina refractories, in which maximum alumina content can be as high as __________ percent.
A 55
B 70
C 80
D 90
Maximum shrinkage in volume occurring during burning/firing of dried refractories may be as high as __________ percent.
A 10
B 15
C 20
D 30

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