REFRACTORY TECHNOLOGY QUIZ

Mullite is chemically represented by

Al2O₃ . 2SiO₂

2Al2O₃ . 3SiO₂

3Al2O₃ . 2SiO₂

Al2O₃ . SiO₂

TRUE ANSWER : ?
YOUR ANSWER : ?

Which of the following has the lowest electrical resistivity?

Alumina

Fireclay

Graphite

Zircon

TRUE ANSWER : ?
YOUR ANSWER : ?

Test piece for determination of RUL of a refractory is heated in a/an

Electric furnace

Oxidising atmosphere

Reducing atmosphere

Neutral atmosphere

TRUE ANSWER : ?
YOUR ANSWER : ?

Basic bricks are not made of

Fireclay

Foresterite

Chromite

Magnesite

TRUE ANSWER : ?
YOUR ANSWER : ?

10 to 30% magnesite is added to chromite to produce chrome-magnesite refractories. Magnesite addition is mainly done to improve the __________ of chromite.

Crushing strength

Spalling resistance

Refractoriness

Resistance to slag

TRUE ANSWER : ?
YOUR ANSWER : ?

Natural silica

All of these

Mainly contains quartz

Transforms to other allotropic forms i.e tridymite and cristoballite involving very high volume changes

Is not stable at high temperature

TRUE ANSWER : ?
YOUR ANSWER : ?

Magnesite bricks have poor resistance to attack by __________ slag.

Acid

None of these

Lime

Basic

TRUE ANSWER : ?
YOUR ANSWER : ?

Maximum alumina content in high alumina refractory can be as high as __________ percent.

50

90

70

30

TRUE ANSWER : ?
YOUR ANSWER : ?

Hot face insulating linings of high purity alumina fused mullite are used, where

Presence of iron or silica is harmful

Highly reducing conditions are involved

All of these

Very high temperatures are involved

TRUE ANSWER : ?
YOUR ANSWER : ?

Fusion temperature of pure silica (SiO₂) is __________ °C.

2800

1350

2570

1715

TRUE ANSWER : ?
YOUR ANSWER : ?

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