3041. Spray test determines the __________ of refractories.
resistance to slag penetration
resistance to CO attack
RUL
permanent linear change
✅ The correct answer is option A.
3049. Walls, roofs & combustion chambers of annealing furnaces are made of __________ bricks.
high duty fireclay
silica
mullite
carborundum
✅ The correct answer is option A.
3053. Faster rate of drying of moulded refractories results in high __________ of refractories.
green strength
voids
shrinkage
both (b) and (c)
✅ The correct answer is option D.
3058. Magnesite chrome bricks are used in the
roof lining of basic open hearth & other basic furnaces.
reheating furnaces.
soaking pits.
all (a), (b) and (c).
✅ The correct answer is option D.
3025. Refractory materials are never used in the construction of
segar cones
orton cones
pressure vessels
ovens & retorts
✅ The correct answer is option C.
3032. Chrome magnesite brick is not used for lining the
hearth of soaking pits.
bottom hearth of reheating furnace.
coke oven regenerator.
burning zone of limestone rotary kilns.
✅ The correct answer is option C.
3037. Thoria
has high fusion temperature (> 3000°C) but poor resistance to thermal shock.
has high resistance to basic slags.
which is expensive & radioactive, is used in crucibles for melting high purity metals.
all (a), (b) and (c).
✅ The correct answer is option D.
3042. Thermal spalling mainly occurs during __________ of furnaces.
cooling down
warming up
both (a) & (b)
neither (a) nor (b)
✅ The correct answer is option C.
3047. __________ is the measure of the strength of refractory under the combined effect of temperature & load.
Porosity
RUL
Specific gravity
Thermal conductivity
✅ The correct answer is option B.
3051. Spalling resistance of a refractory can not be increased by
increasing its porosity.
using a coarser grog during its manufacture.
decreasing its thermal co-efficient of expansion.
making it denser.
✅ The correct answer is option D.