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Refractory Technology problems


  • 1. silicon carbide refractories have very low

  • Options
  • A. refractoriness (< 1700°C).
  • B. thermal conductivity.
  • C. resistance to thermal shock.
  • D. none of these.
  • Discuss
  • 2. Cold crushing strength of ordinary fireclay brick is about 950 kg/cm2 . On exposure to a temperature of about 1500°C, its crushing strength may come down to as low as __________ kg/cm2 .

  • Options
  • A. 450
  • B. 250
  • C. 150
  • D. 65
  • Discuss
  • 3. Which of the following is not a neutral refractory?

  • Options
  • A. Silicon carbide
  • B. Magnesite
  • C. Chromite
  • D. Graphite
  • Discuss
  • 4. Silica refractories

  • Options
  • A. crack when subjected to sudden change of temperature.
  • B. can not be used in the dome of hot blast stoves.
  • C. have lower thermal conductivity than fireclay bricks.
  • D. all (a), (b) and (c)
  • Discuss
  • 5. With increase in the alumina content in firebricks, its fusion point (refractoriness)

  • Options
  • A. decreases linearly
  • B. remains unchanged
  • C. increases
  • D. decreases
  • Discuss
  • 6. Which is not an alumino-silicate refractory?

  • Options
  • A. Fireclay bricks.
  • B. Mullite bricks.
  • C. Tar dolomite bricks.
  • D. High alumina bricks.
  • Discuss
  • 7. Which is required in an insulating refractory?

  • Options
  • A. High thermal conductivity
  • B. Low porosity
  • C. Both (a) and (b)
  • D. Neither (a) nor (b)
  • Discuss
  • 8. __________ nozzles are used in continuous casting of steel,

  • Options
  • A. Zircon
  • B. Thoria
  • C. Carborundum
  • D. Beryllia
  • Discuss
  • 9. Except __________ , all other refractories are bad conductors of electricity (i.e, have low electrical conductivity).

  • Options
  • A. fireclay
  • B. carborundum
  • C. graphite
  • D. chromite
  • Discuss
  • 10. Which is the most stable crystalline form of silica at room temperature?

  • Options
  • A. Quartz
  • B. Cristobalite
  • C. Tridymite
  • D. None of these
  • Discuss

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