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  • Question
  • 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

  • Correct Answer
  • cost 


  • Refractory Technology problems


    Search Results


    • 1. 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
    • 2. Which is not a basic refractory?

    • Options
    • A. Chrome magnesite
    • B. Magnesite
    • C. Dolomite
    • D. Silicon carbide
    • Discuss
    • 3. 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
    • 4. 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
    • 5. 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
    • 6. 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
    • 7. 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
    • 8. Spray test determines the __________ of refractories.

    • Options
    • A. resistance to slag penetration
    • B. resistance to CO attack
    • C. RUL
    • D. permanent linear change
    • Discuss
    • 9. Natural rubber is obtained from latex, which is a colloidal dispersion of rubber in water. Which of the following is used as a coagulant in latex?

    • Options
    • A. Ammonium alum
    • B. Potassium alum
    • C. both a & b
    • D. neither a nor b
    • Discuss
    • 10. Transistor parts and refrigerator components are normally made of

    • Options
    • A. polystyrene
    • B. polyester
    • C. high density polythene
    • D. polyurathane
    • Discuss


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