CERAMICS the synthetic material for std 8 to 12

Ceramic Pot

Ceramics :

Clay materials, such as chinaware, porcelain and bricks, are collectively known as ceramics.
All these are being traditionally manufactured and used for over several centuries.
The word ceramic is derived from a Greek word ceremos which means earthen pot.
Preparation of porcelain : 

The raw materials required for the preparation of porcelain are whit clay, sand and feldspar [K2O AI2O3 6SIO2].
Finely powdered mixture of raw materials are mixed with water.The homogeneous mixture is called slip. Slip is pressed with filter paper to remove excess water. Then the slip is moulded into desired shapes and dried. The dried articles are heated in a furnace at about 1873K.
Remember
Clay is the mixture containing aluminium silicate in high quantities. It is formed by the weathering of silicate rocks by the action of air, rain and corbon dioxide.
The fired articles are porous.
These pores are plugged by glazing.
Glazing imparts an attractive look.
Chemicals like born, alumina and smooth silica the uniform spreading of coat.
Pre-determined quantity of metal oxides are added while glazing.
Which gives desired colour to the porcelain.
Uses of porcelain : 

Household articles. Decorative materials. Insulating parts of electric devices. Sanitary items and Laboratory equipments.

Porcelain uses

POINTS TO REMEMBER

Synthetic materials are manufactured by using natural raw materials.
Synthetic materials are plastics, cement, glass, fibers and ceramics.
Polymers are compounds formed by the union of many simple monomers.
Polymerisation is a process of uniting two or more simple compounds to obtain a new compound.
Addition polymerization is a process in which several molecules join together to form a giant molecule.
Polythene, polyvinyl chloride and nylon are examples for polymers.
Plastic is a synthetic material manufactured by polymerization of organic substances.

Polyvinyl chloride and polystyrene are thermoplastics.
Bakelite, silicones are thermosettings.
To avoid the hazards of plastics the usage of plastics should be abandon stage b stage.
The raw materials of cement are clay, lime stone.
Gypsum slows down the rapid setting of cement.
The method of hardening of cement by treating with ater is known as curring.
The raw materials used in the manufacture of glass are sand, limestone and sodium carbonate.
The different types of glass are soda glass, borosilicate glass, lead glass.
Coloured glass, safety glass and fiber glass.
The process of slow cooling of glass is known as annealing.
The raw materials of ceramics are whit clay. Sand and feldspar.
Porcelain is used to prepare decorative materials.
Glazing imparts an attractive look and also plug the pores.

Cement as Synthetic materials with clay and lime stone For std 10 to 12 CBSE

CEMENT
Cement is an important synthetic material. It is the chief component of building materials. Chemically, cement is a mixture of calcium silicate and calcium aluminate, with small amout of gypsum salt.
The essential raw materials used in the manufacture of cement are clay and lime stone. Gypsum (calcium sulphate) is used to regulate setting rate.

Note
Cement resembles a type of lime stone available in port land. J. Aspadin gave the name port land cement in 1824.

Manufacture of cement : 

Manufacture of  Cement 

Finely powdered ground clay and limestone are mixed with water. This homogeneous mixture is called slurry. It is introduced into a rotary kiln (Fig). Hot air at Hot air at about 1873K is blown from the lower end of the rotary kiln. Due to high temperature the water present in the slurry evaporates. At this temperature clay and lime stone combine chemically to form cement balls.
1. Slurry tank
2. Vapourising zone
3. Rotary kiln
4. Combustion zone
5. Hot air
6. Clinker collector

The cement balls so formed are called clinkers. Clinkers. Clinkers are taken out of the kiln and cooled. Clinkers are then finely powdered by grinding and mixed with 3% gypsum. Gypsum slows down the rapid setting of cement. 

Setting and curing : Cement sets into a hard mass when mixed with water. Therefore it makes an excellent binding material in construction work. The mixture of sand and cement along with water undergoes many complex changes. The first stage of setting takes place within 24 hours after adding water to the cement. The second stage of setting requires about two weeks.

The subsequent setting of cement is achieved by adding water. The method of hardeing cement by treating it with water is known as curing. During curing cement absorbs water. Calcium silicate and aluminates of cement are converted into a colloidal gel. This process is exothermic and hence it requires continuous water treatment.

Cement concrete 
The mixture of cement, gravel and sand in the ratio of 1:2:4 or 1:3:6 is known as concrete. An iron skeleton inside concrete gives mechanical strength to the structure.

More: 

Synthetic Materials