Which one of the following is a neutral refractory?

Silliminite (Al₂O₃.SiO₂) refractory, which is a neutral refractory, is not used in

A

Pottery furnace

B

Glass melting furnace

C

Crucibles

D

Gas retorts

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

Dry mix hydraulic compositions of refractory aggregates with suitable bonding materials are called refractory

A

Mortars

B

Cements

C

Castables

D

None of these

If a refractory contains high content of silicon, it means refractory is

A

Acidic

B

Basic

C

Neutral

D

Brittle

Ceramics make excellent refractory materials. A material is said to be refractory if it:

A

resists the flow of electric current

B

has high refractive index

C

retains its strength at high temperatures

D

all of the mentioned

Refractory timber catches fire readily while non-refractory timber does not catch fire readily.

A

True

B

False

A furnace is made of a refractory brick wall of thickness 0.5 metre and thermal conductivity 0.7 W/m.°K For the same temperature drop and heat loss, this refractory wall can be replaced by a layer of diatomaceous earth of thermal conductivity 0.14 W/m.K and thickness __________ metre.

A

0.01

B

0.1

C

0.25

D

0.5

Which of the following is not a neutral refractory?

A

Silicon carbide

B

Magnesite

C

Chromite

D

Graphite

Which of the following is an example of a neutral refractory?

A

Dolomite

B

Magnesia

C

Silica

D

Chromite

Which is a neutral refractory?

A

Graphite

B

Magnesite chrome

C

Silica

D

Magnesia

Which one of the following is a neutral refractory?

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