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  • Question
  • 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.

  • Correct Answer
  • Refractories used in muffle furnace should have low thermal conductivity. 


  • Refractory Technology problems


    Search Results


    • 1. 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
    • 2. 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
    • 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
    • 4. 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
    • 5. Which is not a high alumina refractory?

    • Options
    • A. Mullite
    • B. Corrundum
    • C. Bauxite
    • D. Dolomite
    • Discuss
    • 6. 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
    • 7. Which of the following impurities reduces the refractoriness of magnesite bricks?

    • Options
    • A. Al2O3
    • B. CaO
    • C. SiO2
    • D. all (a), (b) & (c)
    • Discuss
    • 8. 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
    • 9. Refractory bricks having lower porosity have

    • Options
    • A. high insulating properties
    • B. low heat capacity
    • C. low thermal conductivity
    • D. greater strength
    • Discuss
    • 10. Refractoriness under loads (RUL) is quite close to the fusion temperature (PCE) for __________ bricks.

    • Options
    • A. fireclay
    • B. silica
    • C. dolomite
    • D. very low alumina
    • Discuss


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