Refractory Objective Question and Answer - Set 10 - ObjectiveBooks

Refractory Objective Question and Answer - Set 10

Practice Test: Question Set - 10

1. Except ________, all other refractories are bad conductors of electricity (i.e, have low electrical conductivity).
    (A) Fireclay
    (B) Carborundum
    (C) Graphite
    (D) Chromite

2. Colour of fireclay bricks is
    (A) Light buff to reddish buff
    (B) Yellow
    (C) Black
    (D) None of these

3. Refractoriness of a typical silica brick corresponds to Segar cone number, '32', which is equivalent to a temperature of _________ °C.
    (A) 1380
    (B) 1520
    (C) 1710
    (D) 1915

4. Slide gates in teeming laddie used for steel pouring in ingot moulds is lined with _________ bricks.
    (A) Bakelite impregnated or fused periclase
    (B) Silica
    (C) Semi-silica
    (D) Fireclay

5. With increase in the alumina content in firebricks, its fusion point (refractoriness)
    (A) Decreases linearly
    (B) Remains unchanged
    (C) Increases
    (D) Decreases

6. Highest melting (m.p = 3070°C) oxide refractory is
    (A) Alumina
    (B) Thoria
    (C) Zirconia
    (D) Magnesia

7. Insulating refractories should have
    (A) High porosity
    (B) Low thermal conductivity
    (C) Both (a) and (b)
    (D) Neither (a) not (b)

8. Dilatometer is used for the determination of __________ of refractories.
    (A) Modulus of rupture
    (B) Permanent linear change
    (C) Resistance to CO attack
    (D) RUL

9. Which is the stable form of silica below 870°C?
    (A) Tridymite
    (B) Cristobalite
    (C) Quartz
    (D) None of these

10. Refractoriness under loads (RUL) is quite close to the fusion temperature (PCE) for _________ bricks.
    (A) Fireclay
    (B) Silica
    (C) Dolomite
    (D) Very low alumina

11. Which of the following is not a neutral refractory?
    (A) Silicon carbide
    (B) Magnesite
    (C) Chromite
    (D) Graphite

12. The maximum linear expansion of silica bricks during firing is about ________ percent.
    (A) 0.5
    (B) 1
    (C) 2
    (D) 3.5

13. Firing temperature is minimum (1250-1400 °C) for ________ bricks.
    (A) Fireclay
    (B) Direct bonded basic
    (C) Silica
    (D) Magnesite

14. Hot blast main (carrying air at 1000°C) in blast furnace are lined with __________ bricks.
    (A) Silica
    (B) Fireclay
    (C) Magnesite
    (D) Zirconia

15. Electrical resistor bars are made of
    (A) Silicon carbide
    (B) Alumina
    (C) Zirconia
    (D) Graphite

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