Spalling of silica bricks occurs due to abrupt volume changes, when it is cooled below a temperature of ______________ °C?
A. 770
B. 570
C. 270
D. 70
Stoichiometry
Which property of refractories is the most important for top section of the blast furnace ?
Which property of refractories is the most important for top section of the blast furnace ?
A. Resistance to abrasion
B. Resistance to slag penetration
C. Stability of volume at high temperature
D. Resistance to corrosion by slag
Roof of a basic electric furnace is made of ______________ bricks?
Roof of a basic electric furnace is made of ______________ bricks?
A. Superduty fireclay
B. Silica
C. Chromite
D. None of these
Outer combustion chamber of blast furnace stove is lined with _______________ bricks?
Outer combustion chamber of blast furnace stove is lined with _______________ bricks?
A. Fireclay
B. Silica
C. Chrome magnesite
D. Zirconia
Magnesite refractories are used for the construction of those furnaces, which are_______________?
Magnesite refractories are used for the construction of those furnaces, which are_______________?
A. Not required to resist the corrosive action of basic slag
B. Not subjected to fluctuation in temperature
C. Used for raising & maintaining high temperature
D. Both B. and C.
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 ?
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
Test piece for determination of RUL of a refractory is heated in a/an__________________?
Test piece for determination of RUL of a refractory is heated in a/an__________________?
A. Oxidising atmosphere
B. Reducing atmosphere
C. Electric furnace
D. Neutral atmosphere
With increase in the alumina content, the refractoriness of high alumina refractories_________________?
With increase in the alumina content, the refractoriness of high alumina refractories_________________?
A. Increases
B. Decreases
C. Remain same
D. May increase or decrease
Thermal diffusivity of a refractory brick is high, when its ______________ is high?
Thermal diffusivity of a refractory brick is high, when its ______________ is high?
A. Density
B. Specific heat
C. Thermal conductivity
D. None of these
Fusion point of a basic refractory material is________________?
Fusion point of a basic refractory material is________________?
A. Reduced by the addition of acid oxides
B. Increased by the addition of acid oxides
C. Not affected by the addition of acid oxides
D. Always less than 1000°C