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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