Discussion
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- Question
Which of these statement is correct?
Options- A. Conversion of quartz to tridymite is associated with 16% volume increase.
- B. Conversion of tridymite to crystoballite involves very large expansion in volume.
- C. both (a) and (b).
- D. neither (a) nor (b).
- Correct Answer
- neither (a) nor (b).
- 1. RUL of refractories depends on the
Options- A. chemical composition.
- B. physical structure.
- C. presence of impurities like iron & alkali.
- D. all (a), (b) and (c). Discuss
- 2. Presence of MgO in alumino-silicate refractories __________ its refractoriness.
Options- A. increases
- B. lowers
- C. does not affect
- D. either (a) or (b); depends on its quantity Discuss
- 3. Firing temperature is minimum (1250-1400 °C) for __________ bricks.
Options- A. fireclay
- B. direct bonded basic
- C. silica
- D. magnesite Discuss
- 4. Fireclay bricks are not used in the
Options- A. beehive coke oven.
- B. by-product coke oven walls.
- C. combustion chamber of B.F. stoves.
- D. coke oven regenerators. Discuss
- 5. Which is the stable form of silica between 1470°C and the melting point 1713°C?
Options- A. Cristobalite
- B. Tridymite
- C. Quartz
- D. None of these Discuss
- 6. Which property of refractories is the most important for top section of the blast furnace?
Options- A. Resistance to abrasion.
- B. Resistance to slag peneration.
- C. Stability of volume at high temperature.
- D. Resistance to corrosion by slag. Discuss
- 7. Which is not a basic refractory?
Options- A. Chrome magnesite
- B. Magnesite
- C. Dolomite
- D. Silicon carbide Discuss
- 8. Resistance to slag attack of a refractory
Options- A. depends on the nature of slag & refractory.
- B. decreases at higher temperature.
- C. decreases, if defective joints & cracks exist in the refractory.
- D. all (a), (b) and (c). Discuss
- 9. Beryllia (which is used in making crucibles for melting uranium & thorium) is superior to alumina in all respects for high temperature (> 1900°C ) use, except
Options- A. cost
- B. electrical conductivity
- C. thermal conductivity
- D. fusion point Discuss
- 10. With increase in the porosity, thermal spalling resistance of fireclay brick
Options- A. increases
- B. decreases
- C. remains same
- D. may increase or decrease Discuss
Refractory Technology problems
Search Results
Correct Answer: all (a), (b) and (c).
Correct Answer: lowers
Correct Answer: fireclay
Correct Answer: by-product coke oven walls.
Correct Answer: Cristobalite
Correct Answer: Resistance to abrasion.
Correct Answer: Silicon carbide
Correct Answer: all (a), (b) and (c).
Correct Answer: cost
Correct Answer: increases
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