Refractory Questions and Answers MCQ - Set 05 - ObjectiveBooks

Refractory Questions and Answers MCQ - Set 05

Practice Test: Question Set - 05

1. Carbon bricks are not used in the lining of the
    (A) Combustion chamber of blast furnace stoves
    (B) Electric furnaces
    (C) Highly chemical resistant equipments
    (D) Blast furnace hearth

2. Refractoriness under load (RUL) is the most important property for the refractory bricks
    (A) At the hearth bottom of the furnace on which stock is placed
    (B) Used for furnace insulation
    (C) Used in the roof of the furnace
    (D) None of these

3. Grog addition in fireclay during brick manufacture is done to
    (A) Reduce its shrinkage on heating
    (B) Impart greater spalling resistance
    (C) Enhance the strength of fired refractories
    (D) All (a), (b) and (c)

4. Pick out the wrong statement.
    (A) Sand & coke is the main raw material for the manufacture of silicon carbide
    (B) Carbon refractories cannot be used in the furnaces operating under reducing conditions
    (C) Mullite can be obtained by the heating of alusite, kyanite or sillimanite
    (D) Silica occurs in nature in all cellular, amorphous or crystalline form

5. Which of the following does not occur during firing/burning of refractories?
    (A) Removal of water of hydration
    (B) Vitrification
    (C) Decrease in crushing strength
    (D) Development of stable mineral form

6. Ganister is a source of the
    (A) Silica
    (B) Periclase
    (C) Lime
    (D) None of these

7. Conversion of silica mineral to Cristobalite is accompanied by reduction in its
    (A) Volume
    (B) Specific gravity
    (C) Both (a) & (b)
    (D) Neither (a) nor (b)

8. Which is required in an insulating refractory?
    (A) High thermal conductivity
    (B) Low porosity
    (C) Both (a) and (b)
    (D) Neither (a) nor (b)

9. Magnesite chrome bricks are used in the
    (A) Roof lining of basic open hearth & other basic furnaces
    (B) Reheating furnaces
    (C) Soaking pits
    (D) All (a), (b) and (c)

10. Sillimanite is a __________ refractory.
    (A) Basic
    (B) Neutral
    (C) High alumina
    (D) Insulating

11. Silica bricks are attacked by basic slags at high temperature. Which of the following is not used solely as a binding material?
    (A) Aluminium phosphate
    (B) Water
    (C) Lime
    (D) Plaster of Paris

12. Carbon refractories
    (A) Do not burn/oxidize, when exposed to air on heating
    (B) Are not attacked by slags, as they are not wetted by melts
    (C) Do not resist temperature fluctuations
    (D) Have extremely low thermal & electrical conductivities

13. Periclase is
    (A) Crystalline form of MgO
    (B) MgCO3
    (C) ZrSO4
    (D) Amorphous magnesite

14. Refractoriness under load (RUL) of fireclay bricks (under a load of 2 kg/cm2) is __________ °C.
    (A) 500
    (B) 1000
    (C) >1350
    (D) >2000

15. RUL of refractories depends on the
    (A) Chemical composition
    (B) Physical structure
    (C) Presence of impurities like iron & alkali
    (D) All (a), (b) and (c)

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