Practice Test: Question Set - 15
1. Hot metal runner in blast furnace are lined with __________ bricks.
- (A) Silica
- (B) Carborundum
- (C) Fireclay
- (D) Magnesite
2. Which is an acidic refractory?
- (A) Magnesite
- (B) Dolomite
- (C) Fireclay
- (D) Chrome magnesite
3. Fireclay bricks are not used in the
- (A) Beehive coke oven
- (B) By-product coke oven walls
- (C) Combustion chamber of B.F. stoves
- (D) Coke oven regenerators
4. Which is a neutral refractory?
- (A) Graphite
- (B) Magnesite chrome
- (C) Silica
- (D) Magnesia
5. High porosity refractory bricks have
- (A) Poor resistance to the penetration of molten
slag, metal & flue gases
- (B) Poor heat conductivity & low strength
- (C) Better thermal spalling resistance
- (D) All (a), (b) and (c)
6. Which is not an acidic refractory?
- (A) Silica
- (B) Fireclay
- (C) High alumina refractory
- (D) Carbon black
7. Fireclay bricks are used in the
- (A) Coke ovens regenerator
- (B) Outer lining of L.D. converter
- (C) Hearth bottom of blast furnace
- (D) Coke oven walls
8. Magnesite refractories are generally not used in the
- (A) Electric furnace walls
- (B) Steel melting furnace
- (C) Open hearth furnace
- (D) Burning zone of cement kilns
9. Fusion point of a basic refractory material is
- (A) Reduced by the addition of acid oxides
- (B) Increased by the addition of acid oxides
- (C) Not affected by the addition of acid oxides
- (D) Always less than 1000°C
10. Thermal conductivity of refractory bricks
- (A) Increases with decrease in porosity
- (B) Decreases with decreases in porosity
- (C) Is independent of its porosity and is maximum for insulating bricks
- (D) Increases with the amount of air entrapped in
pores
11. Thermal diffusivity of a refractory brick is high, when its __________ is high.
- (A) Density
- (B) Specific heat
- (C) Thermal conductivity
- (D) None of these
12. Which form of silica has the highest specific gravity?
- (A) Quartz
- (B) Cristobalite
- (C) Tridymite
- (D) All have the same specific gravity
13. With increase in the alumina content, the refractoriness of high alumina refractories
- (A) Increases
- (B) Decreases
- (C) Remain same
- (D) May increase or decrease
14. Pick out the wrong statement.
- (A) Refractories used in muffle furnace should have
low thermal conductivity
- (B) The electrical resistivity of refractories drops
rapidly with rise in temperature
- (C) For reducing spalling tendency, the refractory should be well fired
and its porosity should be more
- (D) Refractoriness under load (RUL) of a refractory
is always less than its refractoriness
15. Test piece for determination of RUL of a refractory is heated in a/an
- (A) Oxidizing atmosphere
- (B) Reducing atmosphere
- (C) Electric furnace
- (D) Neutral atmosphere
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