REFRACTORIES
@ Refractory :-
Any material that can withstand high temperatures, without softening or suffering a deformation in shape, mainly used in crucible, ladles, kilns, furnace etc
# Character :-
- Tolerate as high temperature in which they placed
- Heat, Flame resistant
- Crackproff, not deform easily
- Temperature variation stable
- Chemical and physical agent inert
@ Classification of Refractories :-
1. Acid refractories :-
Having acid material like alumina and silica,
- they easily attacked by basic material
2. Basic refractories :-
Having basic material like CaO, MgO etc
- Easily attacked by acidic material
3. Neutral refractories :-
Made by weakly acid/base
# Properties :-
- Tolerancy :-
Ability of refractories to withstand the heat without appreciable deformation
* Refractories expressed in term of Pyrometric cone equivalent
- Strength :-
Refractories material must posses high mechanical strength ,even operating in high temperature
* For determining applying load R.U.L test performed
- Dimensional stability :-
Refractories May be resistance of a material to any volume changes, and if dimension change it would be temporary or reversible
- Chemical inertness :-
Chemically inactive in use and does not easily form fusible product with slag, fuel ashes, furnace etc
- Thermal expansion :-
Refractories Having least possible thermal expansion
- Thermal conductivity :-
It should have good thermal conductivity
- Resistance to erosion :-
It should be have resistance to erosion or corrode material for better performance
- Low Electrical conducting :-
Refractories have low electric conductivity for better performance
- Permeability :-
No permeablility tolerate in refractories
# Failure of refractories :-
* If gives above temperature than optimum temperature
* If refractories get high thermal expansion
* Heavy weight
* When basic and acidic refractory used in basic and acid nature
@ ManufacturinG :-
1. Crushing :-
Crushing of big large lump of raw material
2. Grinding :-
Grinding done after crushing to change crushing material to powered form
3. Screening :-
Purify the refractory raw material
4. Storage :-
Screening pure material stored in storage bins
5. Mixing :-
Mixing of desired material to raw material
6. Moulding :-
Now moulding done by proper mechanical or physical method
7. Drying :-
Removing of moisture from desired product
8. Firing :-
Firing done for stabilize and strengthen their structure
@ Common Refractory Bricks :-
i) Silica Bricks :-
Contain 90-95% SiO2 and about 2% lime is added during grinding to furnish the bond
Final product receive by cooling of cristobalite which gives tridymite,then mixture of tridymite and cristobalite gives final brick
ii) Fireclay brick :-
Made from finely ground soft plastic material fireclay with powered calcined fireclay
# Properties :-
- light yellow to reddish brown colour
- slightly acidic character
- Quite high acidic strength
iii) High alumina brick :-
Prepared by mixing of calcined bauxite with Clay bind
iv) Magnetic brick :-
Prepare by calcined magneside powder with caustic magnesia
V) Dolomite brick :-
Made by calcined dolomite with silicate binder
vi) Caustic brick :-
Prepared by crushed coke with tar
vii) Chromite brick :-
Prepared by crushed chromite mixed with little Clay
viii) Carborundum brick :-
Made by sand +coke + saw dust and salt
ix) zirconia brick :-
X) Beryllia brick
@ Cermets :-
Hot pressed sintered material, consisting combination of ceramin and metal
# Properties :-
- High thermal conductivity
- High shock resistantance
- High shapeability
@ Insulating Refractories :-
@ Refractory :-
Any material that can withstand high temperatures, without softening or suffering a deformation in shape, mainly used in crucible, ladles, kilns, furnace etc
# Character :-
- Tolerate as high temperature in which they placed
- Heat, Flame resistant
- Crackproff, not deform easily
- Temperature variation stable
- Chemical and physical agent inert
@ Classification of Refractories :-
1. Acid refractories :-
Having acid material like alumina and silica,
- they easily attacked by basic material
2. Basic refractories :-
Having basic material like CaO, MgO etc
- Easily attacked by acidic material
3. Neutral refractories :-
Made by weakly acid/base
# Properties :-
- Tolerancy :-
Ability of refractories to withstand the heat without appreciable deformation
* Refractories expressed in term of Pyrometric cone equivalent
- Strength :-
Refractories material must posses high mechanical strength ,even operating in high temperature
* For determining applying load R.U.L test performed
- Dimensional stability :-
Refractories May be resistance of a material to any volume changes, and if dimension change it would be temporary or reversible
- Chemical inertness :-
Chemically inactive in use and does not easily form fusible product with slag, fuel ashes, furnace etc
- Thermal expansion :-
Refractories Having least possible thermal expansion
- Thermal conductivity :-
It should have good thermal conductivity
- Resistance to erosion :-
It should be have resistance to erosion or corrode material for better performance
- Low Electrical conducting :-
Refractories have low electric conductivity for better performance
- Permeability :-
No permeablility tolerate in refractories
# Failure of refractories :-
* If gives above temperature than optimum temperature
* If refractories get high thermal expansion
* Heavy weight
* When basic and acidic refractory used in basic and acid nature
@ ManufacturinG :-
1. Crushing :-
Crushing of big large lump of raw material
2. Grinding :-
Grinding done after crushing to change crushing material to powered form
3. Screening :-
Purify the refractory raw material
4. Storage :-
Screening pure material stored in storage bins
5. Mixing :-
Mixing of desired material to raw material
6. Moulding :-
Now moulding done by proper mechanical or physical method
7. Drying :-
Removing of moisture from desired product
8. Firing :-
Firing done for stabilize and strengthen their structure
@ Common Refractory Bricks :-
i) Silica Bricks :-
Contain 90-95% SiO2 and about 2% lime is added during grinding to furnish the bond
Final product receive by cooling of cristobalite which gives tridymite,then mixture of tridymite and cristobalite gives final brick
ii) Fireclay brick :-
Made from finely ground soft plastic material fireclay with powered calcined fireclay
# Properties :-
- light yellow to reddish brown colour
- slightly acidic character
- Quite high acidic strength
iii) High alumina brick :-
Prepared by mixing of calcined bauxite with Clay bind
iv) Magnetic brick :-
Prepare by calcined magneside powder with caustic magnesia
V) Dolomite brick :-
Made by calcined dolomite with silicate binder
vi) Caustic brick :-
Prepared by crushed coke with tar
vii) Chromite brick :-
Prepared by crushed chromite mixed with little Clay
viii) Carborundum brick :-
Made by sand +coke + saw dust and salt
ix) zirconia brick :-
X) Beryllia brick
@ Cermets :-
Hot pressed sintered material, consisting combination of ceramin and metal
# Properties :-
- High thermal conductivity
- High shock resistantance
- High shapeability
@ Insulating Refractories :-
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