INTRODUCTION OF REFRACTORIES

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REFRACTORIES

INTRODUCTION OF REFRACTORIES :

Refractory comes from a French word “refractaire” meaning high melting. Any material that persues an unusually high melting point and acts as heat-resisting barriers between high and low temperature zones are called Refractories .

The value of refractories is judged from its performance in a particular situation . Quality and Quantity of refractories depends on the 3 phases  i.e  solid , liquid and pores and also on their chemical , physical , thermal  and mineralogical properties.

Refractories are used in glass making , ceramic industries etc where they are used to line interiors of furnaces that process materials at high temperature.

->Refractories used must be temperature  resistant , corrosion resistant , physical wear or  abrasion resistant and resistant to thermal shock.

->Most of the refractory products are porus with large no of varying size of the materials .The presence of pores can reduce the weight bearing strength of products but it can also reduce susceptibility to thermal shock.

There are 2 different forms of refractory materials:-

 <1>Shaped refractories and

<2>Unshaped refractories

Shaped Refractories :- The refractories available maintain proper shape and size for convenience in construction.Mostly the refractory material are available in rectangular brick shape.

Unshaped Refractories:-The unshaped refractory materials form joint-less lining and are grouped as monolithic.Unshaped refractories are available in powder form called castables.

->The refractory consist of single compounds like silica or alumina and has melting points as:-

Silica (SIO2)-1723 degree C

Alumina (Al2O3)-2050 degree C

Mullite (71.8% AL2O3,28.2%SIO2)-1996 degree C

->The important constituents of refractories being alumina and silica are categorised as:-

->Fireclay refractory

->High alumina refractory

->Silical refractory

->Mullite refractory

The most important property of refractory material is that  It must have bulk density and thermal conductivity .

QUESTIONS AND ANSWERS :

QUE > What do you mean by refractory and refractories ?

ANS > Refractory comes from a French word “refractaire” meaning high melting. Any material that persues an unusually high melting point and acts as heat-resisting barriers between high and low temperature zones are called Refractories .

QUE >  What are the different forms of refractories and define them ?

ANS > 

There are 2 different forms of refractory materials:-

 <1>Shaped refractories and

<2>Unshaped refractories

Shaped Refractories :- The refractories available maintain proper shape and size for convenience in construction.Mostly the refractory material are available in rectangular brick shape.

Unshaped Refractories:-The unshaped refractory materials form joint-less lining and are grouped as monolithic.Unshaped refractories are available in powder form called castables.

QUE > Name two important constituents of refractories and how are they categorised ?

ANS >

The important constituents of refractories are alumina and silica are they are  categorised as:-

->Fireclay refractory

->High alumina refractory

->Silical refractory

->Mullite refractory.

INTRODUCTION OF REFRACTORIESREFRACTORIESRefractory ProductsShaped refractoriesUnshaped refractories

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