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Refractory Technology problems

  • 1. An ideal refractory should have high

  • Options
  • A. spalling rate
  • B. fusion point
  • C. shrinkage ability
  • D. none of these
    • Discuss
  • 2. Highest melting (m.p = 3070°C) oxide refractory is

  • Options
  • A. alumina
  • B. thoria
  • C. zirconia
  • D. magnesia
    • Discuss
  • 3. SiO2 percentage in firebrick is about

  • Options
  • A. 35-40
  • B. 55-60
  • C. 80-85
  • D. >94
    • Discuss
  • 4. Maximum apparent porosity of magnesite bricks is about __________ percent.

  • Options
  • A. 8
  • B. 24
  • C. 44
  • D. 58
    • Discuss
  • 5. Mullite is chemically represented by

  • Options
  • A. Al2O3 . 2SiO2
  • B. 3Al2O3 . 2SiO2
  • C. Al2O3 . SiO2
  • D. 2Al2O3 . 3SiO2
    • Discuss
  • 6. Graphite or carbon refractories

  • Options
  • A. exihibit wetting characteristics.
  • B. should be used in neutral or reducing atmosphere.
  • C. exhibit high shrinkage on thermal treatment.
  • D. are not resistant to corrosion by slag.
    • Discuss
  • 7. Dilatometer is used for the determination of __________ of refractories.

  • Options
  • A. modulus of rupture
  • B. permanent linear change
  • C. resistance to CO attack
  • D. RUL
    • Discuss
  • 8. The maximum linear expansion of silica bricks during firing is about __________ percent.

  • Options
  • A. 0.5
  • B. 1
  • C. 2
  • D. 3.5
    • Discuss
  • 9. Upper portion of hot metal mixer are lined with mullite bricks, which helps in resisting the

  • Options
  • A. washing action of metal.
  • B. corrosion by layer of slag.
  • C. both (a) & (b).
  • D. neither (a) nor (b).
    • Discuss
  • 10. Use of higher percentage of lime for bonding silica bricks, reduces their

  • Options
  • A. strength
  • B. abrasion resistance
  • C. both (a) & (b)
  • D. neither (a) nor (b)
    • Discuss

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