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.
Refractory Technology MCQs
32. Silica refractories are not used in
coke oven walls.
beehive coke ovens.
dome and upper portion of B.F. stoves.
open hearth furnace roof.
✅ The correct answer is option B.
33. Because of its very high refractoriness of the order of __________ °C, silicon carbide refractories are used in zinc smelting furnace, muffle furnace and for supporting the wares in tunnel kilns.
1800
2200
2400
2700
✅ The correct answer is option D.
34. Lower wall courses of soaking pits are made of __________ bricks to avoid the action of molten slag & scale.
chrome or magnesite
silicon carbide
silica
lowduty fireclay
✅ The correct answer is option A.
35. Refractoriness under load (RUL) of fireclay bricks (under a load of 2 kg/cm2 ) is __________ °C.
500
1000
>1350
>2000
✅ The correct answer is option C.
36. An indication of degree of firing in silica brick is its
specific gravity
fusion point
RUL
none of these
✅ The correct answer is option A.
37. Roof of a basic open hearth furnace is lined with __________ bricks.
silica
fireclay
dolomite
magnesite
✅ The correct answer is option A.
38. Magnesite bricks have poor resistance to attack by __________ slag.
lime
basic
acid
none of these
✅ The correct answer is option C.
39. Thermal conductivity of refractory bricks
increases with decrease in porosity.
decreases with decreases in porosity.
is independent of its porosity and is maximum for insulating bricks.
increases with the amount of air entrapped in pores.
✅ The correct answer is option A.
40. __________ nozzles are used in continuous casting of steel,
Zircon
Thoria
Carborundum
Beryllia
✅ The correct answer is option A.