Which is the stable form of silica between 1470°C and the melting point 1713°C ?
A. Cristobalite
B. Tridymite
C. Quartz
D. None of these
Refractory Technology
Maximum safe working temperature for fireclay bricks is about __________ °C?
Maximum safe working temperature for fireclay bricks is about __________ °C?
A. 1150
B. 1300
C. 1450
D. 1550
Skull is not formed on the carbon blocks in the hearth of a blast furnace, when it becomes cold, because of its_______________?
Skull is not formed on the carbon blocks in the hearth of a blast furnace, when it becomes cold, because of its_______________?
A. Non-wetting characteristic
B. High thermal conductivity
C. High crushing strength
D. None of these
‘Super refractories’ are made from pure____________________?
‘Super refractories’ are made from pure____________________?
A. Carbides
B. Oxides
C. Borides
D. Nitrides
Magnesite chrome refractories____________________?
Magnesite chrome refractories____________________?
A. Have better spalling resistance than chrome magnesite refractories
B. Have very low thermal co-efficient of expansion
C. Are not at all resistant to the corrosive action of iron oxide
D. Have very low (50 kg/cm2) cold crushing strength (C.C.S.), and cannot be used in metalcase
form
Use of higher percentage of lime for bonding silica bricks, reduces their__________________?
Use of higher percentage of lime for bonding silica bricks, reduces their__________________?
A. Strength
B. Abrasion resistance
C. Both A. & B.
D. Neither A. nor B.
Addition of grog in fireclay brick during its manufacture is advantageous, because it results in_____________________?
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.
Pyrometric cone equivalent (PCE) of a refractory is the measure of its_________________?
Pyrometric cone equivalent (PCE) of a refractory is the measure of its_________________?
A. Spalling resistance
B. Fusion point
C. Resistance to slag penetration
D. Resistance to carbon monoxide attack
Ramming masses are used for____________________?
Ramming masses are used for____________________?
A. Obtaining monolithic working faces
B. Repairing construction of various furnace parts
C. Both A. & B.
D. Neither A. nor B.
Furnace atmosphere for softening temperature determination of refractories (in which Seger Cones are placed) should be __________________?
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.