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Chemical Engineering :: Refractory Technology

  1. Maximum shrinkage in volume occurring during burning/firing of dried refractories may be as high as __________ percent.

  2. A.
    10
    B.
    15
    C.
    20
    D.
    30

  3. Porosity of fireclay refractories is __________ percent.

  4. A.
    5-10
    B.
    10-25
    C.
    25-35
    D.
    35-50

  5. SiO2 percentage in firebrick is about

  6. A.
    35-40
    B.
    55-60
    C.
    80-85
    D.
    >94

  7. Porosity is induced in insulating refractories by adding

  8. A.
    powdered naphthalene.
    B.
    ammonium chloride/sulphate.
    C.
    calcium phosphate.
    D.
    all (a), (b) and (c).

  9. Magnesite bricks have poor resistance to attack by __________ slag.

  10. A.
    lime
    B.
    basic
    C.
    acid
    D.
    none of these

  11. Zirconia refractories are not used in

  12. A.
    making sheaths for thermocouple.
    B.
    lining high temperature ceramic kilns.
    C.
    furnaces subjected to fluctuating temperature.
    D.
    high frequency induction furnaces in the form of inductors.

  13. Carbon refractories

  14. A.
    do not burn/oxidise, 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.

  15. Magnesite refractories have low resistance to

  16. A.
    attack by basic slag.
    B.
    abrasion.
    C.
    disintegration on sudden change of temperature.
    D.
    both (b) and (c).

  17. Which property is important for bricks used in the combustion chamber & dome of blast furnace stoves ?

  18. A.
    High refractoriness.
    B.
    High resistance to spalling.
    C.
    High strength and density.
    D.
    All (a), (b) and (c).

  19. The maximum linear expansion of silica bricks during firing is about __________ percent.

  20. A.
    0.5
    B.
    1
    C.
    2
    D.
    3.5