Refractory Technology Multiple Choice Questions - Set 04 - ObjectiveBooks

Refractory Technology Multiple Choice Questions - Set 04

Practice Test: Question Set - 04

1. Tar dolomite bricks are used in the
    (A) Basic Bessemer converter
    (B) Basic open hearth furnace
    (C) Electric furnaces
    (D) All (a), (b) and (c)

2. Zirconia refractory
    (A) Does not react with basic slags
    (B) Is produced from baddeleyite
    (C) Cannot be used as an insulator
    (D) Has poor electrical conductivity at high temperature

3. Cold crushing strength of fireclay bricks is about __________ kgf/cm2.
    (A) 50-100
    (B) 100-150
    (C) 200-400
    (D) 500-1000

4. Carbon refractories have very high
    (A) Wetting characteristics
    (B) Refractoriness
    (C) Thermal conductivity
    (D) Both (b) and (c)

5. Sillimanite (Al2O3.SiO2) refractory, which is a neutral refractory, is not used in
    (A) Pottery furnace
    (B) Glass melting furnace
    (C) Crucibles
    (D) Gas retorts

6. An ideal refractory should have high
    (A) Spalling rate
    (B) Fusion point
    (C) Shrinkage ability
    (D) None of these

7. Pick out the wrong statement.
    (A) Electrical conductivity of refractory is not important, when these are to be used in electrical furnaces
    (B) Graphite and metals are the good electrical conductor among the refractories and others are all electrical insulators
    (C) Refractories used for lining electrical furnaces should ordinarily have very low electrical conductivity
    (D) Electrical conductivity of porous refractory material is low

8. Fusion point of an acidic refractory material is
    (A) Increased by the addition of basic oxides
    (B) Reduced by the addition of basic oxides
    (C) Not affected by the addition of basic oxides
    (D) Always more than 2500°C

9. Rate of slag attack on refractories increases with rise in temperature due to the
    (A) Decreased viscosity of slag
    (B) Increased thermal conductivity of brick
    (C) Oxidizing condition in the furnace
    (D) None of these

10. Segar cones are used for the determination of __________ of refractories.
    (A) Softening temperature
    (B) Spalling resistance
    (C) Electrical conductivity
    (D) Resistance to slag attack

11. Tar bonded dolomite bricks
    (A) Are stored under controlled temperature & humidity to avoid hydration
    (B) Are used in outer lining of L.D. converters
    (C) Have poorer hydration resistance than pitch bonded bricks
    (D) All (a), (b) and (c)

12. Porosity is induced in insulating refractories by adding
    (A) Powdered naphthalene
    (B) Ammonium chloride/sulphate
    (C) Calcium phosphate
    (D) All (a), (b) and (c)

13. Which furnace consumes maximum refractory annually in an integrated steel plant ?
    (A) Soaking pit
    (B) Blast furnace
    (C) L.D. converter
    (D) Coke ovens

14. Machine moulding of dry mixture of refractories requires a pressure of the order of __________ kg/cm2.
    (A) 10
    (B) 100
    (C) 500
    (D) 1000

15. Which of the following bricks should not be used, if the furnace is to be used intermittently?
    (A) Firebricks
    (B) Silica bricks
    (C) Silicon carbide bricks
    (D) Sillimanite

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