141. Electrical resistor bars are made of
silicon carbide
alumina
zirconia
graphite
✅ The correct answer is option A.
Refractory Technology MCQs
142. Cold crushing strength of ordinary fireclay brick is about 950 kg/cm2 . On exposure to a temperature of about 1500°C, its crushing strength may come down to as low as __________ kg/cm2 .
450
250
150
65
✅ The correct answer is option D.
143. Dilatometer is used for the determination of __________ of refractories.
modulus of rupture
permanent linear change
resistance to CO attack
RUL
✅ The correct answer is option B.
144. Ganister is a source of the
silica
periclase
lime
none of these
✅ The correct answer is option A.
145. Carbon refractories are exclusively used in the
hearth of blast furnace.
walls of coke oven.
regenerators of coke oven.
side wall of soaking pits.
✅ The correct answer is option A.
146. Silica refractories
crack when subjected to sudden change of temperature.
can not be used in the dome of hot blast stoves.
have lower thermal conductivity than fireclay bricks.
all (a), (b) and (c)
✅ The correct answer is option A.
147. With increase in the density of silica refractories, its
resistance to slag attack increases.
spalling resistance reduces.
both (a) and (b).
neither (a) nor (b).
✅ The correct answer is option C.
148. Alumina-graphite bricks are used for lining the
slide gate in teeming laddies.
continuous casting systems.
both (a) and (b).
neither (a) nor (b).
✅ The correct answer is option C.
149. The main raw material for manufacture of silicon carbide refractories is
corrundum
carborundum
bauxite
periclase
✅ The correct answer is option B.
150. Refractories subjected to alternate cycles of heating & cooling are liable to loose their resistance to
thermal spalling
slag attack
fusion under load
CO attack
✅ The correct answer is option A.