Refractory Questions & Answers - Set 09 - ObjectiveBooks

Refractory Questions & Answers - Set 09

Practice Test: Question Set - 09

1. PCE value (Segar cone) of Superduty refractories is more than 33, which is equivalent to a temperature of _________ °C.
    (A) 1520
    (B) 1630
    (C) 1670
    (D) 1730

2. 'Spinel', a refractory mineral is chemically represented as
    (A) MgAl2O4
    (B) MgAl2O3
    (C) MgSO4
    (D) MgAl2O3.2H2O

3. Spray test determines the _________ of refractories.
    (A) Resistance to slag penetration
    (B) Resistance to CO attack
    (C) RUL
    (D) Permanent linear change

4. With increase in the density of silica refractories, its
    (A) Resistance to slag attack increases
    (B) Spalling resistance reduces
    (C) Both (a) and (b)
    (D) Neither (a) nor (b)

5. Fireclay refractories have
    (A) Low co-efficient of thermal expansion
    (B) Poor thermal spalling resistance
    (C) Tendency to expand unduly high during firing
    (D) Very high cost

6. Mixing of ground refractory material and water is done in a _________ mill.
    (A) Pug
    (B) Ball
    (C) Tube
    (D) Rod

7. Dolomite bricks have good resistance to attack by
    (A) Molten steel
    (B) Iron oxide
    (C) Lime slag
    (D) None of these

8. Silicon carbide refractories are used in the
    (A) Muffle furnace
    (B) Zinc smelting furnace
    (C) Ceramic recuperators
    (D) All (a), (b) and (c)

9. Zirconia refractories are not used in
    (A) Making sheaths for thermocouple
    (B) Lining high temperature ceramic kilns
    (C) Furnaces subjected to fluctuating temperature
    (D) High frequency induction furnaces in the form of inductors

10. Firing temperature of magnesite bricks is about ________ °C.
    (A) 800-1000
    (B) 1000-1200
    (C) 1600-1800
    (D) 2400-2600

11. The highest melting pure oxide (m.p. > 3000°C) is
    (A) Thoria
    (B) Alumina
    (C) Beryllia
    (D) Zirconia

12. Which of the following is not an acidic refractory?
    (A) Silica bricks
    (B) Fireclay bricks
    (C) Bauxite bricks
    (D) Magnesia bricks

13. The largest consumer of refractories is the _________ industry.
    (A) Cement
    (B) Metallurgical
    (C) Fertilizer
    (D) Power

14. Grog
    (A) Contains both alumina and silica
    (B) Is crushed firebrick
    (C) Is a non-plastic material
    (D) All (a), (b) and (c)

15. Crushing strength of a refractory
    (A) Increases with rise in service temperature
    (B) Decreases with rise in service temperature
    (C) Is unaffected with change in service temperature
    (D) Decreases with increase in porosity

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