151. With decrease in porosity, the __________ of the refractories decreases.
strength
thermal conductivity
spalling resistance
none of these
✅ The correct answer is option C.
Refractory Technology MCQs
152. Water content in ground refractory material to be shaped into bricks by hand moulding is about __________ percent.
5
20
40
55
✅ The correct answer is option B.
153. Which of the following consumes the maximum tonnage of refractories annually in an integrated steel plant ?
Soaking pits
Ceheating furnace
L.D. converter
Rotary lime kiln
✅ The correct answer is option C.
154. Chromite refractories
are bonded with lime and clay.
(free from silica) have better thermal fatigue resistance than silica and magnesite refractories.
are resistant to basic slag.
all (a), (b) and (c).
✅ The correct answer is option D.
155. Spalling of silica bricks occurs due to abrupt volume changes, when it is cooled below a temperature of __________ °C.
770
570
270
70
✅ The correct answer is option C.
156. Resistance to slag attack of a refractory
depends on the nature of slag & refractory.
decreases at higher temperature.
decreases, if defective joints & cracks exist in the refractory.
all (a), (b) and (c).
✅ The correct answer is option D.
157. Ramming masses are used for
obtaining monolithic working faces.
repairing construction of various furnace parts.
both (a) & (b).
neither (a) nor (b).
✅ The correct answer is option C.
158. Thoria is an expensive refractory material and is radioactive in nature. Thorium oxide is used in the manufacture of
segar cones.
muffles for muffle furnaces.
insulating bricks.
crucibles used for melting of high purity metals.
✅ The correct answer is option D.
159. Outer combustion chamber of blast furnace stove is lined with __________ bricks.
fireclay
silica
chrome magnesite
zirconia
✅ The correct answer is option A.
160. Cold crushing strength of fireclay bricks is about __________ kgf/cm2.
50-100
100-150
200-400
500-1000
✅ The correct answer is option C.