Refractory Technology

1. 'Spinel', a refractory mineral is chemically represented as

1. M_gAl₂O₄
2. M_gAl₂O₃
3. M_gSO₄
4. M_gAl₂O₃.2H₂O

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2. 'Super refractories' are made from pure

1. Carbides
2. Oxides
3. Borides
4. Nitrides

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

1. High alumina
2. Fireclay
3. Thoria
4. Silicon carbide

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4. _________ bricks should not be used in oxidising atmosphere.

1. Tar dolomite
2. Carbon
3. Silica
4. Fireclay

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5. _________ is not a single oxide-refractory.

1. Zirconia
2. Silicon carbide
3. Magnesia
4. None of these

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6. _________ is the measure of the strength of refractory under the combined effect of temperature & load.

1. Porosity
2. RUL
3. Specific gravity
4. Thermal conductivity

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7. _________ nozzles are used in continuous casting of steel,

1. Zircon
2. Thoria
3. Carborundum
4. Beryllia

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8. _________ of carbon blocks in the hearth of blast furnace helps in avoiding skull formation, when it becomes cold.

1. High thermal conductivity
2. Low porosity
3. Non-wetting characteristics
4. High density

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9. 10 to 30% magnesite is added to Chromite to produce chrome-magnesite refractories. Magnesite addition is mainly done to improve the _________ of Chromite.

1. Spalling resistance
2. Refractoriness
3. Crushing strength
4. Resistance to slag

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