Refractory Technology MCQ

Test your knowledge with important Refractory Technology MCQ and their applications. These MCQs are beneficial for competitive exams too. Explore 30 + more Refractory Technology MCQs at Bissoy

• Zirconia refractory
  ক

  Does not react with basic slags

  খ

  Is produced from baddeleyite

  গ

  Can not be used as an insulator

  ঘ

  Has poor electrical conductivity at high temperature
• Zircon refractories have
  ক

  Low co-efficient of expansion

  খ

  High RUL (1600°C) and refractoriness (> 2000°C)

  গ

  High spalling resistance

  ঘ

  All of the above
• High density refractory bricks have lower
  ক

  Spalling resistance

  খ

  Thermal conductivity

  গ

  Fusion point

  ঘ

  Slag penetration resistance
• Fireclay bricks are never used in the
  ক

  Beehive oven

  খ

  Coke oven walls

  গ

  Zinc roaster

  ঘ

  Lead blast furnace
• Which one expands on heating?
  ক

  Silica bricks

  খ

  Fireclay bricks

  গ

  Both A & B

  ঘ

  Neither A nor B
• Which is a basic refractory?
  ক

  Fireclay

  খ

  Silica

  গ

  Chrome magnesite

  ঘ

  None of these
• 10 to 30% magnesite is added to chromite to produce chrome-magnesite refractories. Magnesite addition is mainly done to improve the __________ of chromite.
  ক

  Spalling resistance

  খ

  Refractoriness

  গ

  Crushing strength

  ঘ

  Resistance to slag
• A steel member used in the furnace construction to take the thrust of the brickwork is called
  ক

  Buckstay

  খ

  Breast wall

  গ

  Armouring

  ঘ

  Baffle
• Porosity is induced in insulating refractories by adding
  ক

  Powdered naphthalene

  খ

  Ammonium chloride/sulphate

  গ

  Calcium phosphate

  ঘ

  All of the above
• Silica refractories
  ক

  Crack when subjected to sudden change of temperature

  খ

  Can not be used in the dome of hot blast stoves

  গ

  Have lower thermal conductivity than fireclay bricks

  ঘ

  All of the above
• Crushing strength of a refractory
  ক

  Increases with rise in service temperature

  খ

  Decreases with rise in service temperature

  গ

  Is unaffected with change in service temperature

  ঘ

  Decreases with increase in porosity
• Which of the following bricks should not be used, if the furnace is to be used intermit-tantly?
  ক

  Firebricks

  খ

  Silica bricks

  গ

  Silicon carbide bricks

  ঘ

  Sillimanite
• With increase in the alumina content, the refractoriness of high alumina refractories
  ক

  Increases

  খ

  Decreases

  গ

  Remains same

  ঘ

  May increase or decrease
• Spalling tendency of refractories is reduced by increasing its
  ক

  Porosity

  খ

  Specific gravity

  গ

  Thermal conductivity

  ঘ

  Strength
• Maximum apparent porosity of magnesite bricks is about __________ percent.
  ক

  8

  খ

  24

  গ

  44

  ঘ

  58
• Cold crushing strength of fireclay bricks is about __________ kgf/cm².
  ক

  50 - 100

  খ

  100 - 150

  গ

  200 - 400

  ঘ

  500 - 1000
• High refractorinness of refractory bricks means, that it has a
  ক

  High spalling resistance

  খ

  Low spalling resistance

  গ

  High resistance to fusion

  ঘ

  Low porosity
• Bottom of basic open hearth furnace are constructed of
  ক

  Dead burnt magnesite ramming mass

  খ

  Porous fireclay bricks

  গ

  Semi-silica bricks

  ঘ

  Silicon carbide bricks
• __________ of carbon blocks in the hearth of blast furnace helps in avoiding skull formation, when it becomes cold.
  ক

  High thermal conductivity

  খ

  Low porosity

  গ

  Non-wetting characteristics

  ঘ

  High density
• Rate of slag attack on refractories increases with rise in temperature due to the
  ক

  Decreased viscosity of slag

  খ

  Increased thermal conductivity of brick

  গ

  Oxidising condition in the furnace

  ঘ

  None of these
• Which of the following does not occur during firing/burning of refractories?
  ক

  Removal of water of hydration

  খ

  Vitrification

  গ

  Decrease in crushing strength

  ঘ

  Development of stable mineral form
• An insulating refractory brick should have high porosity and low thermal conductivity. Which of the following is not used for inducing porosity in the insulating refractory bricks during its manufacture?
  ক

  Cork

  খ

  Saw dust

  গ

  Sand

  ঘ

  Chemically prepared foam
• Refractoriness/fusion points of 'superduty' refractories is __________ °C.
  ক

  1520-1630

  খ

  1630-1670

  গ

  > 1730

  ঘ

  > 2000
• Refractories are dried in the
  ক

  Rotary kilns

  খ

  Tunnel kilns

  গ

  Sun

  ঘ

  None of these
• SiO₂ percentage in firebrick is about
  ক

  35 - 40

  খ

  55 - 60

  গ

  80 - 85

  ঘ

  > 94
• 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
  ক

  Cost

  খ

  Electrical conductivity

  গ

  Thermal conductivity

  ঘ

  Fusion point
• Graphite or carbon refractories
  ক

  Exihibit wetting characteristics

  খ

  Should be used in neutral or reducing atmosphere

  গ

  Exhibit high shrinkage on thermal treatment

  ঘ

  Are not resistant to corrosion by slag
• Ramming masses are used for
  ক

  Obtaining monolithic working faces

  খ

  Repairing construction of various furnace parts

  গ

  Both A & B

  ঘ

  Neither A nor B
• Silliminite (Al₂O₃.SiO₂) refractory, which is a neutral refractory, is not used in
  ক

  Pottery furnace

  খ

  Glass melting furnace

  গ

  Crucibles

  ঘ

  Gas retorts
• Refractory castables are used for
  ক

  Producing monolithic linings

  খ

  Patch work

  গ

  Minimising the number of joints in the structure

  ঘ

  All of the above