Refractory Technology problems
- 1. Which is not a high alumina refractory?
Options- A. Mullite
- B. Corrundum
- C. Bauxite
- D. Dolomite Discuss
Correct Answer: Dolomite
- 2. Ramming masses are used for
Options- A. obtaining monolithic working faces.
- B. repairing construction of various furnace parts.
- C. both (a) & (b).
- D. neither (a) nor (b). Discuss
Correct Answer: both (a) & (b).
- 3. __________ is the measure of the strength of refractory under the combined effect of temperature & load.
Options- A. Porosity
- B. RUL
- C. Specific gravity
- D. Thermal conductivity Discuss
Correct Answer: RUL
- 4. 10 to 30% magnesite is added to chromite to produce chrome-magnesite refractories. Magnesite addition is mainly done to improve the __________ of chromite.
Options- A. spalling resistance
- B. refractoriness
- C. crushing strength
- D. resistance to slag Discuss
Correct Answer: spalling resistance
- 5. High alumina refractory compared to fireclay bricks have
Options- A. less load bearing capacity.
- B. less resistance to slag attack.
- C. low refractoriness.
- D. high resistance to thermal shock and creep. Discuss
Correct Answer: high resistance to thermal shock and creep.
- 6. Pick out the wrong statement.
Options- A. Refractories used in muffle furnace should have low thermal conductivity.
- B. The electrical resistivity of refractories drops rapidly with rise in temperature.
- C. For reducing spalling tendency, the refractory should be well fired and its porosity should be more.
- D. Refractoriness under load (RUL) of a refractory is always less than its refractoriness. Discuss
Correct Answer: Refractories used in muffle furnace should have low thermal conductivity.
- 7. Addition of zircon to silica refractory brick improves its
Options- A. crushing strength
- B. resistance to slag attack
- C. both (a) and (b)
- D. neither (a) nor (b) Discuss
Correct Answer: resistance to slag attack
- 8. Which of the following impurities reduces the refractoriness of magnesite bricks?
Options- A. Al2O3
- B. CaO
- C. SiO2
- D. all (a), (b) & (c) Discuss
Correct Answer: all (a), (b) & (c)
- 9. Crushing strength of a refractory
Options- A. increases with rise in service temperature.
- B. decreases with rise in service temperature.
- C. is unaffected with change in service temperature.
- D. decreases with increase in porosity. Discuss
Correct Answer: decreases with rise in service temperature.
- 10. Refractory bricks having lower porosity have
Options- A. high insulating properties
- B. low heat capacity
- C. low thermal conductivity
- D. greater strength Discuss
Correct Answer: greater strength
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