Refractory Materials pdf Test Questions - Set 06 - ObjectiveBooks

Refractory Materials pdf Test Questions - Set 06

Practice Test: Question Set - 06

1. Natural silica
    (A) Mainly contains quartz
    (B) Is not stable at high temperature
    (C) Transforms to other allotropic forms i.e. Tridymite and Cristobalite involving very high volume changes
    (D) All (a), (b) and (c)

2. Which one contains maximum percentage of Al2O3?
    (A) Firebrick
    (B) Sillimanite
    (C) Magnesite
    (D) Aluminous firebrick

3. Spalling tendency of refractories is reduced by increasing its
    (A) Porosity
    (B) Specific gravity
    (C) Thermal conductivity
    (D) Strength

4. Which is not a basic refractory?
    (A) Chrome magnesite
    (B) Magnesite
    (C) Dolomite
    (D) Silicon carbide

5. Which is not a high alumina refractory?
    (A) Mullite
    (B) Corundum
    (C) Bauxite
    (D) Dolomite

6. Silica refractories
    (A) Crack when subjected to sudden change of temperature
    (B) Cannot be used in the dome of hot blast stoves
    (C) Have lower thermal conductivity than fireclay bricks
    (D) All (a), (b) and (c)

7. Which brick undergoes maximum shrinkage on drying?
    (A) Tar bonded dolomite bricks
    (B) Fireclay bricks
    (C) Magnesite bricks
    (D) Chromite bricks

8. Firing of refractory brick is done to
    (A) Dehydrate the dried refractory
    (B) Develop stable mineral forms in them
    (C) Form ceramic bonds necessary for development of high crushing strength in the finished product
    (D) All (a), (b) and (c)

9. 10 to 30% magnesite is added to Chromite to produce chrome-magnesite refractories. Magnesite addition is mainly done to improve the __________ of Chromite.
    (A) Spalling resistance
    (B) Refractoriness
    (C) Crushing strength
    (D) Resistance to slag

10. Ferromagnetic ceramic material is not used in the
    (A) Thermal insulation
    (B) Transformers
    (C) Magnetic switches
    (D) Television sets

11. Furnace atmosphere for softening temperature determination of refractories (in which Seger Cones are placed) should be
    (A) Oxidizing
    (B) Neutral
    (C) Either (a) or (b)
    (D) Neither (a) nor (b)

12. Which one expands on heating?
    (A) Silica bricks
    (B) Fireclay bricks
    (C) Both (a) & (b)
    (D) Neither (a) nor (b)

13. Ramming masses are used for
    (A) Obtaining monolithic working faces
    (B) Repairing construction of various furnace parts
    (C) Both (a) & (b)
    (D) Neither (a) nor (b)

14. _________ nozzles are used in continuous casting of steel,
    (A) Zircon
    (B) Thoria
    (C) Carborundum
    (D) Beryllia

15. Pyrometric cone equivalent (PCE) of a refractory is the measure of its
    (A) Spalling resistance
    (B) Fusion point
    (C) Resistance to slag penetration
    (D) Resistance to carbon monoxide attack

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