JSS2 Third Term Basic Technology Lesson Note – Processing of Materials

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 WEEK EIGHT:        PROCESSING OF MATERIALS

TOPIC:          METALS

CONTENT:

• Production of metals: smelting, casting, etc.
• Carbon properties of steels
• Metal Alloys
• Clay, ceramics and glass

Metallic materials are materials which are referred to as good conductors of heat and electricity. Metals are gotten from Iron ore which is the raw material for metal production. The Iron Ore is dug from the ground along with the impurities (coke, hot air, limestone with Iron Ore).

When the Iron Ore is dug up from the ground, it cannot be used as it contains some impurities, it undergoes certain processes during which these impurities are removed and other substances are added. Since these impurities cannot be removed from iron-ore in its solid state, it is converted into a liquid state by heating. Thus, process is known as smelting. The equipment used for this process is called a furnace. After removing these impurities from Iron Ore, the product left is called Pig-Iron. The Pig iron in its ordinary state cannot be used without further processing; this is because pig iron contains saturated iron and carbon. This is weak and can break easily. Hence, it forms the basis of all ferrous metals containing about 45% carbon.

In order to render pig iron usable such as cast Iron, steels and wrought Iron, the amount of carbon it contains must be reduced.

Cast Iron: This is obtained when pig Iron is put into a cupola furnace. In this furnace, the carbon content is reduced to about 3.5%. The molten Iron is then poured from the furnace into a container, called mould, so as to solidify it. This process of pouring molten

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