Q.1
Magnesite chrome refractories
Q.2
Refractoriness/fusion points of 'superduty' refractories is __________ °C.
Q.3
High alumina refractory compared to fireclay bricks have
Q.4
Which is not an alumino-silicate refractory?
Q.5
Fireclay bricks are used in the
Q.6
Skull is not formed on the carbon blocks in the hearth of a blast furnace, when it becomes cold, becaus of its
Q.7
Dilatometer is used for the determination of __________ of refractories.
Q.8
Refractory bricks with lower permeability is produced by using
Q.9
__________ nozzles are used in continuous casting of steel,
Q.10
'Spinel', a refractory mineral is chemically represented as
Q.11

To resist spalling tendency, a refractory should have

  • greater diffusivity.
  • low specific heat.
  • low thermal co-efficient of expansion.
  • all (a), (b) and (c).
Q.12

Mullite is chemically represented by

  • Al2O3 . 2SiO2
  • 3Al2O3 . 2SiO2
  • Al2O3 . SiO2
  • 2Al2O3 . 3SiO2
Q.13

Which of the following bricks should not be used, if the furnace is to be used intermit-tantly ?

  • Firebricks
  • Silica bricks
  • Silicon carbide bricks
  • Sillimanite
Q.14

Porosity of silica bricks varies from __________ percent.

  • 5 to 10
  • 20 to 30
  • 45 to 60
  • 60 to 75
Q.15

Maximum shrinkage in volume occurring during burning/firing of dried refractories may be as high as __________ percent.

  • 10
  • 15
  • 20
  • 30
Q.16

Cold crushing strength of fireclay bricks is about __________ kgf/cm2.

  • 50-100
  • 100-150
  • 200-400
  • 500-1000
Q.17

__________ bricks are used in the burning zone of a cement rotary kiln.

  • High alumina
  • Fireclay
  • Thoria
  • Silicon carbide
Q.18

Sillimanite is a __________ refractory.

  • basic
  • neutral
  • high alumina
  • insulating
Q.19

Refractory castables are used for

  • producing monolithic linings.
  • patch work.
  • minimising the number of joints in the structure.
  • all (a), (b) and (c).
Q.20

Colour of fireclay bricks is

  • light buff to reddish buff
  • yellow
  • black
  • none of these
Q.21

Rate of slag attack on refractories increases with rise in temperature due to the

  • decreased viscosity of slag.
  • increased thermal conductivity of brick.
  • oxidising condition in the furnace.
  • none of these.
Q.22

Carbon bricks are not used in the lining of the

  • combustion chamber of blast furnace stoves.
  • electric furnaces.
  • highly chemical resistant equipments.
  • blast furnace hearth.
Q.23

Porosity of fireclay refractories is __________ percent.

  • 5-10
  • 10-25
  • 25-35
  • 35-50
Q.24

Spalling tendency of refractories is reduced by increasing its

  • porosity
  • specific gravity
  • thermal conductivity
  • strength
Q.25

Carbon refractories are exclusively used in the

  • hearth of blast furnace.
  • walls of coke oven.
  • regenerators of coke oven.
  • side wall of soaking pits.
Q.26

Furnace atmosphere for softening temperature determination of refractories (in which segar cones are placed) should be

  • oxidising
  • neutral
  • either (a) or (b)
  • neither (a) nor (b)
Q.27

High refractorinness of refractory bricks means, that it has a

  • high spalling resistance.
  • low spalling resistance.
  • high resistance to fusion.
  • low porosity.
Q.28

Conversion of silica mineral to cristobalite is accompanied by reduction in its

  • volume
  • specific gravity
  • both (a) & (b)
  • neither (a) nor (b)
Q.29

The largest consumer of refractories is the __________ industry.

  • cement
  • metallurgical
  • fertiliser
  • power
Q.30

Which of the following is not a high alumina refractory material ?

  • Kyanite
  • Sillimanite
  • Diaspore
  • Periclase
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