Lesson Notes By Weeks and Term - Junior Secondary School 1

FIRST TERM

SUBJECT: BASIC TECHNOLOGY

CLASS: JSS1

REFERENCE MATERIALS

• NERDC, Basic Technology for JSS, Book 1
• EVANS, Basic Technology for JSS, Book 1

WEEK SIX AND SEVEN

TOPIC: IDENTIFICATION OF METALS

CONTENT

• Definition and Properties of Metal
• Classes of Metal
• Processing of Metal
• Uses of Metal

DEFINITION OF METAL

METAL is a type of solid mineral substance that is usually hard and shiny. It conducts heat and electricity can travel through it.

Metals have characteristics which are different from those of the non-metals such as wood, plastics ceramics, rubber etc

PROPERTIES OF METAL

Metals can be identified by the following physical properties:

1. Conductivity: Some metals have the ability to conduct heat and electricity.
2. Fusibility: Some metals have the ability to be melted and cast into shapes.
3. Magnetic: Some metals have the ability to attract iron.
4. Ductility: Some metals have the ability to be drawn or stretched out into wires without breaking.
5. Brittleness: Some metals have the ability to break or crack , when hit on the ground
6. Malleability: Some metals have the ability to be hammered or beaten into shape without cracking.
7. Toughness: Some metals have the ability to withstand (resist) bending, breaking, cracking or stretching.
8. Density: Some metals have weight and volume.
9. Colour (lustre): Some metals have the ability of having a shining appearance when polished.

CLASSES OF METAL

The metals used in engineering can be classified into categories

1. Ferrous metals and their alloys
2. Non-ferrous metals and their alloys

FERROUS METALS AND THEIR ALLOYS

This group of metals contains iron. The metals are, therefore, magnetic. Examples include wrought iron, cast iron and various grades of steel.

NON-FERROUS METALS AND THEIR ALLOYS

This group of metals have no iron . These metals are therefore not magnetic. Examples are aluminum, copper, brass etc.

EVALUATION

1. State five properties of metal.
2. Differentiate between ferrous and non-ferrous metal.

PROCESSING METALS

Most metals do not occur in a pure state. They are usually combined with other metals and earthly impurities to form what is called mineral ore. The ore is then mined and processed to extract the metal of interest. The extraction process differs from metal to metal.

1. Casting:

Casting is the process of melting and pouring molten metal into the mould to take the shape of the mould when it cools down or solidifies.

1. Smelting:

Smelting is the process of extracting metals from iron-ore dug from the ground .

1. Annealing:

Annealing is the process by which metals can be softened.

USES OF METALborder="1" style="width: 350px;">

Alloy metal

composition

Properties

Brass

65%copper and 35%zinc

Soft material

Gilding metal

80% copper and 20 % zinc

Polishes well and no corrosion

Bell metal

78% copper and 22% zinc

Louder in sound than other metals

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Ferrous metals

Uses

Cast iron

Cast iron in the manufacturing of machine parts , pipes, radiators, stoves, engine blocks

Carbon steel

Carbon steels are used in the manufacturing of the automobile bodies gears, hacksaws ,hammers ,drill, knives

Alloy steels

Alloy steels are used in the manufacturing of cables, steels, rail, wires , springs , shoves, ball-bearing, chisels etc.

Wrought Iron

The wrought iron is used in the manufacturing of nails ,horse

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Non-ferrous metal

Uses

Aluminium

Aluminium is used for manufacturing aircraft, cooking pots for its lightness.

Copper

Copper is used for making telephone wires, water heater, pipes ,electric cables.

Zinc

Zinc is used for the coating of iron and steel as a protection against rusting .It is used for wire-fence ,water tank reservoir ,bucket.

Brass

Brass is for making musical instrument screws clocks.

Silver

Silver is for ornament work ,mirror .

Nickel

Nickel is used for plating iron and materials to give a shining slivering appearance . It is also used for making cooking pots and sauce pan.

Lead

Lead is used for making lead pipes , storage batteries , chemicals and cover electric cables.

Tin

Tin is used for making engine bearing, ball-bearing medals, coins , statues and collapsible tubes.

EVALUATION

1. Explain the following methods of processing of metal (i) annealing (ii) smelting (iii) casting.
2. State the uses of the following metals (i) alloy metals (ii) ferrous metals (iii) non-ferrous metals.

READING ASSIGNMENT

Read on Identification of Ceramics, Plastics and Rubber from Introductory Technology (JSS1) by Evans. Pages 32-35

WEEKEND ASSIGNMENT

1. _____ is a type of solid mineral substance that is usually hard and shiny and that heat and electricity can travel through (a) Plastic (b) Rubber (c) Metal (d) Ceramics
2. Some metals have the ability to be hammered or beaten into shape without cracking .This quality is known as (a) malleability (b) ductility (c) toughness (d) fusibility
3. The group of metals that contains iron is known as (a) ferrous metals (b) non-ferrous metals (c) alloys. (d) terrazzo
4. The group of metals that has no iron is not magnetic. Examples are as follow except

(a) aluminium (b) copper (c) steel (d) brass

1. ______ is the process by the which metals can be softened.(a) Casting (b) Smelting (c) Annealing (d) Riveting

THOERY

1. Define and state the properties of metals.
2. State the classes of metals with examples.
3. Explain the following methods of processing of metals (i) annealing (ii) smelting (iii) casting.
4. State the uses of the following metals (i) alloy metals (ii) ferrous metals (iii) non-ferrous metals