Refractory Technology problems
- 1. Thoria is an expensive refractory material and is radioactive in nature. Thorium oxide is used in the manufacture of
Options- A. segar cones.
- B. muffles for muffle furnaces.
- C. insulating bricks.
- D. crucibles used for melting of high purity metals. Discuss
Correct Answer: crucibles used for melting of high purity metals.
- 2. Refractoriness of a typical silica brick corresponds to Segar cone number, '32', which is equivalent to a temperature of __________ °C.
Options- A. 1380
- B. 1520
- C. 1710
- D. 1915 Discuss
Correct Answer: 1710
- 3. Chemically, mullite refractories is
Options- A. 3Al2O3.2SiO2
- B. Al2O3
- C. ZrSO4
- D. ThO2 Discuss
Correct Answer: 3Al2O3.2SiO2
- 4. Which is the stable form of silica below 870°C?
Options- A. Tridymite
- B. Cristobalite
- C. Quartz
- D. None of these Discuss
Correct Answer: Quartz
- 5. Firing of refractory brick is done to
Options- A. dehydrate the dried refractory.
- B. develop stable mineral forms in them.
- C. form ceramic bonds necessary for development of high crushing strength in the finished product.
- D. all (a), (b) and (c). Discuss
Correct Answer: all (a), (b) and (c).
- 6. Maximum alumina content in high alumina refractory can be as high as __________ percent.
Options- A. 30
- B. 50
- C. 70
- D. 90 Discuss
Correct Answer: 90
- 7. Spalling of silica bricks occurs due to abrupt volume changes, when it is cooled below a temperature of __________ °C.
Options- A. 770
- B. 570
- C. 270
- D. 70 Discuss
Correct Answer: 270
- 8. Firing temperature of magnesite bricks is about __________ °C.
Options- A. 800-1000
- B. 1000-1200
- C. 1600-1800
- D. 2400-2600 Discuss
Correct Answer: 1600-1800
- 9. Fireclay bricks are used in the
Options- A. coke ovens regenerator.
- B. outer lining of L.D. converter.
- C. hearth bottom of blast furnace.
- D. coke oven walls. Discuss
Correct Answer: coke ovens regenerator.
- 10. Panel test determines the __________ of refractories.
Options- A. fusion point
- B. spalling resistance
- C. slag penetration resistance
- D. refractoriness under load (RUL) Discuss
Correct Answer: spalling resistance
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