Refractory Technology

10. A steel member used in the furnace construction to take the thrust of the brickwork is called

  1. Buckstay
  2. Breast wall
  3. Armouring
  4. Baffle

Correct answer: (A)

11. Addition of grog in fireclay brick during its manufacture is advantageous, because it results in

  1. Less shrinkage in heating, decreased apparent porosity & increased specific gravity
  2. High strength & thermal spalling resistance
  3. Less addition of water to get a workable plasticity & lesser time required for drying the raw refractories and hence increased rate of production
  4. All (A), (B) and (C)

Correct answer: (D)
All (A), (B) and (C)

12. Addition of zircon to silica refractory brick improves its

  1. Crushing strength
  2. Resistance to slag attack
  3. Both (A) and (B)
  4. Neither (A) nor (B)

Correct answer: (B)
Resistance to slag attack

13. Alumina-graphite bricks are used for lining the

  1. Slide gate in teeming laddies
  2. Continuous casting systems
  3. Both (A) and (B)
  4. Neither (A) nor (B)

Correct answer: (C)
Both (A) and (B)

14. An ideal refractory should have high

  1. Spalling rate
  2. Fusion point
  3. Shrinkage ability
  4. None of these

Correct answer: (B)
Fusion point

15. An indication of degree of firing in silica brick is its

  1. Specific gravity
  2. Fusion point
  3. RUL
  4. None of these

Correct answer: (A)
Specific gravity

16. 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?

  1. Cork
  2. Saw dust
  3. Sand
  4. Chemically prepared foam

Correct answer: (C)

17. Basic bricks are not made of

  1. Fireclay
  2. Magnesite
  3. Forsterite
  4. Chromite

Correct answer: (A)

18. Bauxite calcining rotary kilns are lined with _________ bricks.

  1. Fireclay
  2. Carbon
  3. 85% alumina
  4. Corundum

Correct answer: (C)
85% alumina

19. Because of its very high refractoriness of the order of _________ °C, silicon carbide refractories are used in zinc smelting furnace, muffle furnace and for supporting the wares in tunnel kilns.

  1. 1800
  2. 2200
  3. 2400
  4. 2700

Correct answer: (D)

20. 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

  1. Cost
  2. Electrical conductivity
  3. Thermal conductivity
  4. Fusion point

Correct answer: (A)

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