Properties Of Materials: Metals JSS1 Basic Technology Lesson Note

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 that 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 can conduct heat and electricity.
2.         Fusibility: Some metals can be melted and cast into shapes.
3.         Magnetic:  Some metals can attract iron.
4.       Ductility:  Some metals can be drawn or stretched out into wires without breaking.
5.         Brittleness: Some metals can break  or crack when hit on the ground
6.     Malleability: Some metals can be hammered or beaten into shape without cracking.
7. Toughness: Some metals can withstand (resist) bending, breaking, cracking, or stretching.
8.       Density: Some metals have weight and volume.
9.   Colour (luster): Some metals can have 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 has 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 metals.

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 mold to take the shape of the mold when it cools down or solidifies.

1.         Smelting:

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

1.         Annealing: 

Annealing is the process by which metals can be softened.

USES OF METAL

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.