71. 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.
Refractory Technology MCQs
72. Which of the following is not a neutral refractory ?
Silicon carbide
Magnesite
Chromite
Graphite
✅ The correct answer is option B.
73. Refractories used in/for __________ should have low thermal conductivity.
coke ovens
insulation
regenerators
muffle furnaces
✅ The correct answer is option B.
74. Which of the following is not a high alumina refractory material ?
Kyanite
Sillimanite
Diaspore
Periclase
✅ The correct answer is option D.
75. Refractoriness under load (RUL) is the most important property for the refractory bricks
at the hearth bottom of the furnace on which stock is placed.
used for furnace insulation.
used in the roof of the furnace.
none of these.
✅ The correct answer is option A.
76. Mullite is chemically represented by
Al2O3 . 2SiO2
3Al2O3 . 2SiO2
Al2O3 . SiO2
2Al2O3 . 3SiO2
✅ The correct answer is option B.
77. Machine moulding of dry mixture of refractories requires a pressure of the order of __________ kg/cm2.
10
100
500
1000
✅ The correct answer is option D.
78. High alumina refractories are used in the
dome of blast furnace stoves.
electric arc furnace roof.
glass melting furnaces.
all (a), (b) and (c).
✅ The correct answer is option D.
79. Permeability of bricks is a measure of the
refractoriness.
melting point.
rate at which a fluid will pass through the pores.
expansion during heating.
✅ The correct answer is option C.
80. Beryllia (which is used in making crucibles for melting uranium & thorium) is superior to alumina in all respects for high temperature (> 1900°C ) use, except
cost
electrical conductivity
thermal conductivity
fusion point
✅ The correct answer is option A.