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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