Refractory Technology problems
- 1. 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
Correct Answer: lowers
- 2. 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
Correct Answer: all (a), (b) and (c).
- 3. 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). Discuss
Correct Answer: neither (a) nor (b).
- 4. 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
Correct Answer: Resistance to abrasion.
- 5. Which is not a basic refractory?
Options- A. Chrome magnesite
- B. Magnesite
- C. Dolomite
- D. Silicon carbide Discuss
Correct Answer: Silicon carbide
- 6. 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
Correct Answer: all (a), (b) and (c).
- 7. 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
Correct Answer: cost
- 8. 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
Correct Answer: increases
- 9. Magnesite bricks are used in those parts of furnaces, which are
Options- A. subjected to temperature fluctuation.
- B. required to resist corrosive basic slag.
- C. subjected to high load.
- D. none of these. Discuss
Correct Answer: required to resist corrosive basic slag.
- 10. Spray test determines the __________ of refractories.
Options- A. resistance to slag penetration
- B. resistance to CO attack
- C. RUL
- D. permanent linear change Discuss
Correct Answer: resistance to slag penetration
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