Refractory Technology problems
- 1. Skull is not formed on the carbon blocks in the hearth of a blast furnace, when it becomes cold, becaus of its
Options- A. non-wetting characteristic.
- B. high thermal conductivity.
- C. high crushing strength.
- D. none of these. Discuss
Correct Answer: non-wetting characteristic.
- 2. Walls, roofs & combustion chambers of annealing furnaces are made of __________ bricks.
Options- A. high duty fireclay
- B. silica
- C. mullite
- D. carborundum Discuss
Correct Answer: high duty fireclay
- 3. Water content in ground refractory material to be shaped into bricks by hand moulding is about __________ percent.
Options- A. 5
- B. 20
- C. 40
- D. 55 Discuss
Correct Answer: 20
- 4. A steel member used in the furnace construction to take the thrust of the brickwork is called
Options- A. buckstay
- B. breast wall
- C. armouring
- D. baffle Discuss
Correct Answer: buckstay
- 5. Grog
Options- A. contains both alumina and silica.
- B. iscrushed firebrick.
- C. is a non-plastic material.
- D. all (a), (b) and (c). Discuss
Correct Answer: all (a), (b) and (c).
- 6. With increase in the alumina content, the refractoriness of high alumina refractories
Options- A. increases
- B. decreases
- C. remains same
- D. may increase or decrease Discuss
Correct Answer: increases
- 7. Thermal diffusivity of a refractory brick is high, when its __________ is high.
Options- A. density
- B. specific heat
- C. thermal conductivity
- D. none of these Discuss
Correct Answer: thermal conductivity
- 8. An indication of degree of firing in silica brick is its
Options- A. specific gravity
- B. fusion point
- C. RUL
- D. none of these Discuss
Correct Answer: specific gravity
- 9. Quartz is
Options- A. stable form of silica upto 870°C.
- B. converted to tridymite on firing between 870 to 1470°C.
- C. transformed to crystoballite on heating above 1470°C.
- D. all (a), (b) and (c). Discuss
Correct Answer: all (a), (b) and (c).
- 10. Thoria
Options- A. has high fusion temperature (> 3000°C) but poor resistance to thermal shock.
- B. has high resistance to basic slags.
- C. which is expensive & radioactive, is used in crucibles for melting high purity metals.
- D. all (a), (b) and (c). Discuss
Correct Answer: all (a), (b) and (c).
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