Page 128 - WCS - Electrical

WORKSHOP CALCULATION & SCIENCE - CITS

Copper Alloys

Brass
It is an alloy of copper and zinc. For certain types of brass small quantities of tin or lead are added. The colour
of brass depends on the percentage of the alloying elements. The colour is yellow or light yellow, or nearly white.
It can be easily machined. Brass is also corrosion-resistant.
Brass is widely used for making motor car radiator core and water taps etc. It is also used in gas welding for hard
soldering/brazing. The melting point of brass ranges from 880 to 930oC.

Brasses of different composition are made for various applications.
Bronze
Bronze is basically an alloy of copper and tin. Sometimes zinc is also added for achieving certain special
properties. Its colour ranges from red to yellow. The melting point of bronze is about 1005oC. It is harder than
brass. It can be easily machined with sharp tools. The chip produced is granular. Special bronze alloys are used
as brazing rods.
Bronze of different compositions are available for various applications.
Lead and its alloys
Lead is a very commonly used non-ferrous metal and has a variety of industrial applications.
Lead is produced from its ore ‘GALENA’. Lead is a heavy metal that is silvery in colour when molten. It is soft and
malleable and has good resistance to corrosion. It is a good insulator against nuclear radiation. Lead is resistant
to many acids like sulphuric acid and hydrochloric acid.
It is used in car batteries, in the preparation of solders etc. It is also used in the preparation of paints.
Lead Alloys
Babbit metal
Babbit metal is an alloy of lead, tin, copper and antimony. It is a soft, anti-friction alloy, often used as bearings.
An alloy of lead and tin is used as ‘soft solder’.

Zinc and its alloys
Zinc is a commonly used metal for coating on steel to prevent corrosion. Examples are steel buckets, galvanized
roofing sheets, etc.

Zinc is obtained from the ore-calamine or blende.
Its melting point is 420o C.
It is brittle and softens on heating; it is also corrosion- resistant. Due to this reason it is used for battery containers
and is coated on roofing sheets etc.

Galvanized iron sheets are coated with zinc.
Tin and tin alloys
Tin
Tin is produced from cassiterite or tinstone. It is silvery white in appearance, and the melting point is 231o C. It is
soft and highly corrosion-resistant.
It is mainly used as a coating on steel sheets for the production of food containers. It is also used with other
metals, to form alloys.
Example: Tin with copper to form bronze. Tin with lead to form solder. Tin with copper, lead and antimony to form
Babbit metal.
Aluminium

Aluminium is a non-ferrous metal which is extracted from ‘BAUXITE’. Aluminium is white or whitish grey in colour.
It has a melting point of 660o C. Aluminium has high electrical and thermal conductivity. It is soft and ductile, and

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CITS : WCS - Electrical - Exercise 11