rotary kilns
tunnel kilns
sun
none of these
✅ The correct answer is option B.
Engineering
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3122. Which of the following is not a neutral refractory ?
Silicon carbide
Magnesite
Chromite
Graphite
✅ The correct answer is option B.
3123. Carbon refractories
do not burn/oxidise, when exposed to air on heating.
are not attacked by slags, as they are not wetted by melts.
do not resist temperature fluctuations.
have extremely low thermal & electrical conductivities.
✅ The correct answer is option B.
3124. The highest melting pure oxide (m.p. > 3000°C)is
thoria
alumina
beryllia
zirconia
✅ The correct answer is option A.
3125. With increase in the alumina content, the refractoriness of high alumina refractories
increases
decreases
remains same
may increase or decrease
✅ The correct answer is option A.
3126. PCE value (Segar cone) of superduty refractories is more than 33, which is equivalent to a temperature of __________ °C.
1520
1630
1670
1730
✅ The correct answer is option D.
3127. Which of the following is not a high alumina refractory material ?
Kyanite
Sillimanite
Diaspore
Periclase
✅ The correct answer is option D.
3128. Spalling of a refractory means its
softening.
fracture due to uneven expansion at high temperature.
resistancce to compressive loads.
resistance to chemical action of gases and molten fluxes.
✅ The correct answer is option B.
3129. Refractories used in/for __________ should have low thermal conductivity.
coke ovens
insulation
regenerators
muffle furnaces
✅ The correct answer is option B.
3130. Porosity is induced in insulating refractories by adding
powdered naphthalene.
ammonium chloride/sulphate.
calcium phosphate.
all (a), (b) and (c).
✅ The correct answer is option D.