Refractory Technology MCQ Questions & Answers

91

Pick out the wrong statement.

A) Electrical conductivity of refractory is not important, when these are to be used in electrical furnaces B) Graphite and metals are the good electrical conductor among the refractories and others are all electrical insulators C) Refractories used for lining electrical furnaces should ordinarily have very low electrical conductivity D) Electrical conductivity of porous refractory material is low

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Answer & Solution

Answer: Option A

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92

High refractorinness of refractory bricks means, that it has a

A) High spalling resistance B) Low spalling resistance C) High resistance to fusion D) Low porosity

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Answer & Solution

Answer: Option C

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93

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

A) 50 - 100 B) 100 - 150 C) 200 - 400 D) 500 - 1000

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Answer & Solution

Answer: Option C

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94

Maximum apparent porosity of magnesite bricks is about __________ percent.

A) 8 B) 24 C) 44 D) 58

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Answer & Solution

Answer: Option B

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95

Pick out the wrong statement.

A) Fluxing material like lime is added in clay to reduce the vitrification temperature B) Main constituents of clay are alumina and silica C) Addition of sand in ceramic materials makes it non-plastic, increases its fusion point and reduces its shrinkage on burning D) Vitrification of fireclay material is done to increase its porosity

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Answer & Solution

Answer: Option D

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96

Spalling tendency of refractories is reduced by increasing its

A) Porosity B) Specific gravity C) Thermal conductivity D) Strength

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Answer & Solution

Answer: Option A

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97

With increase in the alumina content, the refractoriness of high alumina refractories

A) Increases B) Decreases C) Remains same D) May increase or decrease

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Answer & Solution

Answer: Option A

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98

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

A) Firebricks B) Silica bricks C) Silicon carbide bricks D) Sillimanite

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Answer & Solution

Answer: Option B

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99

Crushing strength of a refractory

A) Increases with rise in service temperature B) Decreases with rise in service temperature C) Is unaffected with change in service temperature D) Decreases with increase in porosity

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Answer & Solution

Answer: Option B

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100

Silica refractories

A) Crack when subjected to sudden change of temperature B) Can not be used in the dome of hot blast stoves C) Have lower thermal conductivity than fireclay bricks D) All of the above

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Answer & Solution

Answer: Option A

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Refractory Technology MCQ Questions & Answers | Chemical Engineering