Which is a basic refractory?

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

Which is not a basic refractory?

A

Chrome magnesite

B

Magnesite

C

Dolomite

D

Silicon carbide

Fusion point of a basic refractory material is

A

Reduced by the addition of acid oxides

B

Increased by the addition of acid oxides

C

Not affected by the addition of acid oxides

D

Always less than 1000°C

The refractory lining of the bottom in a basic electric arc furnace is made of

A

Silica

B

Alumina

C

Magnesia

D

Fireclay

what is the monthly salary of Rahman ? Statements : 1. Rahman's basic salary is Tk. 100 more Rajan's salary who also serves in Rahman's company. 2. Other allowances drawn by Rajan besides his basic salary are Tk. 2,000 per month which is TK. 50 less than Rahan's salary . 3. Rajan's basic salary is TK. 1550 per month.

A

Only II

B

Only II and III

C

Only I and II

D

All I , II and II

Which of the following is not a high alumina refractory material?

A

Kyanite

B

Sillimanite

C

Diaspore

D

Periclase

Which of the following will happen if the thickness of refractory wall of furnace is increased?

A

Heat loss through furnace wall will increase

B

Temperature inside the furnace will fall

C

Temperature on the outer surface of furnace walls will drop

D

Energy consumption will increase

Ceramic coating material for furnace refractory, which increases its emissivity and thus the radiation heat transfer rate in the furnace, comprises of

A

Graphite powder

B

Thoria

C

Zircon powder

D

Beryllium

Which is a basic refractory?

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