Chemical Engineering - Refractory Technology

21. 

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

Answer: Option C

Explanation:

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22. 

Beryllia (which is used in making crucibles for melting uranium & thorium) is superior to alumina in all respects for high temperature (> 1900°C ) use, except

A. cost
B. electrical conductivity
C. thermal conductivity
D. fusion point

Answer: Option A

Explanation:

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23. 

An insulating refractory brick should have high porosity and low thermal conductivity. Which of the following is not used for inducing porosity in the insulating refractory bricks during its manufacture ?

A. Cork
B. Saw dust
C. Sand
D. Chemically prepared foam

Answer: Option C

Explanation:

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24. 

Firing of refractory brick is done to

A. dehydrate the dried refractory.
B. develop stable mineral forms in them.
C. form ceramic bonds necessary for development of high crushing strength in the finished product.
D. all (a), (b) and (c).

Answer: Option D

Explanation:

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25. 

Chemically, mullite refractories is

A. 3Al2O3.2SiO2
B. Al2O3
C. ZrSO4
D. ThO2

Answer: Option A

Explanation:

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