Refractory Technology MCQs

Question 1

Fireclay refractories

Accepted Answer

All of the above

Answer

Are not resistant to the action of basic slags

Answer

Combine with salts (e.g. chlorides sulphates etc.) & bases (e.g. lime, magnesia etc.) forming fusible aluminates silicates etc

Answer

Shrink during firing

Question 2

Zirconia refractory

Accepted Answer

Is produced from baddeleyite

Answer

Does not react with basic slags

Answer

Can not be used as an insulator

Answer

Has poor electrical conductivity at high temperature

Question 3

Because of its very high refractoriness of the order of __________ °C, silicon carbide refractories are used in zinc smelting furnace, muffle furnace and for supporting the wares in tunnel kilns.

Accepted Answer

2700

Answer

1800

Answer

2200

Answer

2400

Question 4

Pyrometric cone equivalent (PCE) value (Segar cone) of 'superduty refractories' is more than 33 which corresponds to a temperature of __________ °C.

Accepted Answer

1730

Answer

1520

Answer

1630

Answer

1670

Question 5

'Super refractories' are made from pure

Accepted Answer

Oxides

Answer

Carbides

Answer

Borides

Answer

Nitrides

Question 6

Which of the following impurities reduces the refractoriness of magnesite bricks?

Accepted Answer

All of the above

Answer

Al 2 O 3

Answer

CaO

Answer

SiO 2

Question 7

Spalling resistance of a refractory can not be increased by

Accepted Answer

Making it denser

Answer

Increasing its porosity

Answer

Using a coarser grog during its manufacture

Answer

Decreasing its thermal co-efficient of expansion

Question 8

Alumina-graphite bricks are used for lining the

Accepted Answer

Both A & B

Answer

Slide gate in teeming laddies

Answer

Continuous casting systems

Answer

Neither A nor B

Question 9

Thoria is an expensive refractory material and is radioactive in nature. Thorium oxide is used in the manufacture of

Accepted Answer

Crucibles used for melting of high purity metals

Answer

Segar cones

Answer

Muffles for muffle furnaces

Answer

Insulating bricks