Discussion
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- Question
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
- Correct Answer
- Cristobalite
- 1. High porosity refractory bricks have
Options- A. poor resistance to the peneration of molten slag, metal & flue gases.
- B. poor heat conductivity & low strength.
- C. better thermal spalling resistance.
- D. all (a), (b) and (c). Discuss
- 2. Capacity of a refractory brick to withstand-sudden changes in temperature is denoted by the property called
Options- A. spalling resistance.
- B. refractoriness.
- C. refractoriness under load (RUL).
- D. none of these. Discuss
- 3. Chromite refractories
Options- A. are bonded with lime and clay.
- B. (free from silica) have better thermal fatigue resistance than silica and magnesite refractories.
- C. are resistant to basic slag.
- D. all (a), (b) and (c). Discuss
- 4. Test piece for determination of RUL of a refractory is heated in a/an
Options- A. oxidising atmosphere
- B. reducing atmosphere
- C. electric furnace
- D. neutral atmosphere Discuss
- 5. Refractoriness/fusion points of 'superduty' refractories is __________ °C.
Options- A. 1520-1630
- B. 1630-1670
- C. > 1730
- D. > 2000 Discuss
- 6. 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
- 7. Firing temperature is minimum (1250-1400 °C) for __________ bricks.
Options- A. fireclay
- B. direct bonded basic
- C. silica
- D. magnesite Discuss
- 8. 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
- 9. 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
- 10. 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
Refractory Technology problems
Search Results
Correct Answer: all (a), (b) and (c).
Correct Answer: spalling resistance.
Correct Answer: all (a), (b) and (c).
Correct Answer: electric furnace
Correct Answer: > 1730
Correct Answer: by-product coke oven walls.
Correct Answer: fireclay
Correct Answer: lowers
Correct Answer: all (a), (b) and (c).
Correct Answer: neither (a) nor (b).
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