Refractory Technology problems
- 1. Which of the following bricks has the most close values of RUL and PCE?
Options- A. Silica bricks
- B. Fireclay bricks
- C. High alumina bricks
- D. Tar dolomite bricks Discuss
Correct Answer: Silica bricks
- 2. Silica bricks have low spalling resistance below 600°C, due to its
Options- A. very high thermal conductivity.
- B. high co-efficient of expansion upto this temperature.
- C. high thermal diffusivity.
- D. low refractoriness. Discuss
Correct Answer: high co-efficient of expansion upto this temperature.
- 3. Pick out the wrong statement.
Options- A. Sand & coke is the main raw material for the manufacture of silicon carbide.
- B. Carbon refractories can not be used in the furnaces operating under reducing conditions.
- C. Mullite can be obtained by the heating of alusite, kyanite or silimanite.
- D. Silica occurs in nature in all cellular, amorphous or crystalline form. Discuss
Correct Answer: Carbon refractories can not be used in the furnaces operating under reducing conditions.
- 4. Carbon bricks are not used in the lining of the
Options- A. combustion chamber of blast furnace stoves.
- B. electric furnaces.
- C. highly chemical resistant equipments.
- D. blast furnace hearth. Discuss
Correct Answer: combustion chamber of blast furnace stoves.
- 5. Silica refractories are not used in
Options- A. coke oven walls.
- B. beehive coke ovens.
- C. dome and upper portion of B.F. stoves.
- D. open hearth furnace roof. Discuss
Correct Answer: beehive coke ovens.
- 6. Which of the following has the lowest electrical resistivity?
Options- A. Graphite
- B. Fireclay
- C. Alumina
- D. Zircon Discuss
Correct Answer: Graphite
- 7. Segar cones are used for the determination of __________ of refractories.
Options- A. softening temperature
- B. spalling resistance
- C. electrical conductivity
- D. resistance to slag attack Discuss
Correct Answer: softening temperature
- 8. Lower part of hot metal mixer are lined with __________ bricks.
Options- A. superduty fireclay
- B. high alumina
- C. silica
- D. carborundum Discuss
Correct Answer: carborundum
- 9. Pick out the wrong statement.
Options- A. Electrical conductivity of refractory is not important, when these are to be used in electrical furnaces.
- B. Graphite and metals are the good electrical conductor among the refractories and others are all electrical insulators.
- C. Refractories used for lining electrical furnaces should ordinarily have very low electrical conductivity.
- D. Electrical conductivity of porous refractory material is low. Discuss
Correct Answer: Electrical conductivity of refractory is not important, when these are to be used in electrical furnaces.
- 10. Pick out the wrong statement.
Options- A. Fluxing material like lime is added in clay to reduce the vitrification temperature.
- B. Main constituents of clay are alumina and silica.
- C. Addition of sand in ceramic materials makes it non-plastic, increases its fusion point and reduces its shrinkage on burning.
- D. Vitrification of fireclay material is done to increase its porosity. Discuss
Correct Answer: Vitrification of fireclay material is done to increase its porosity.
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