A. Stable form of silica upto 870°C
B. Converted to Tridymite on firing between 870 to 1470°C
C. Transformed to Cristobalite on heating above 1470°C
D. All A., B. and C.
Related Mcqs:
- Periclase is___________________?
A. Crystalline form of MgO
B. MgCO3
C. ZrSO4
D. Amorphous magnesite - The highest melting pure oxide (m.p. > 3000°C)is___________________?
A. Thoria
B. Alumina
C. Beryllia
D. Zirconia - Chrome magnesite bricks are_________________?
A. Acidic in nature
B. Neutral in nature
C. Having higher RUL than silica bricks
D. Made by mixing 30% Chromite and 70% Periclase - Refractory materials are never used in the construction of _________________?
A. Segar cones
B. Orton cones
C. Pressure vessels
D. Ovens & retorts - Most Cermets, which normally have high thermal conductivity and high thermal shock resistance, comprises of ceramic & metallic components of ______________ percent respectively?
A. 80 and 20
B. 20 and 80
C. 50 and 50
D. 60 and 40 - A steel member used in the furnace construction to take the thrust of the brickwork is called___________________?
A. Buckstay
B. Breast wall
C. Armouring
D. Baffle - Pick out the wrong statement?
A. Fluxing material like lime is added in clay to reduce the vitrification temperature
B. Main constituents of clay are alumina and silica
C. Addition of sand in ceramic materials makes it non-plastic, increases its fusion point and
reduces its shrinkage on burning
D. Vitrification of fireclay material is done to increase its porosity - Furnace atmosphere for softening temperature determination of refractories (in which Seger Cones are placed) should be __________________?
A. Oxidising
B. Neutral
C. Either A. or B.
D. Neither A. nor B. - Hot blast main (carrying air at 1000°C) in blast furnace are lined with ______________ bricks?
A. Silica
B. Fireclay
C. Magnesite
D. Zirconia - Permeability of bricks is a measure of the_________________?
A. Refractoriness
B. Melting point
C. Rate at which a fluid will pass through the pores
D. Expansion during heating
