TERM: FIRST TERM
SUBJECT: BASIC TECHNOLOGY
CLASS: JSS 3
TOPIC: PROCESSING OF MATERIALS: ALLOYS
Metals are materials used in producing some equipment used in everyday life. Metals are usually solid but a few ones are liquid or powder form. They are made raw forms called ore.
METHODS OF PROCESSING METALS
Most metals do not occur in a pure state they are usually combined with other metals and earthly impuritiesto form what is called mineral ore. The ore is then mined and processedto extract the metal of interest. The methods of processing metals include:
This 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.
This is the process of extracting metals from iron ore dug from the ground.
This is the process by which metals can be softened.
STAGES OF METAL PRODUCTION
There three stages in the production of metals
STAGE ONE: EXTRACTION STAGE: The rock containing the metal is dug from the ground with drilling and excavating. The rock and the metal mixed togetherare calledthe metal ore(the impure metal)
STAGE TWO: SMELTING STAGE: The metal ore is heated in a furnace( e. g blast furnace ) until the metal melts into liquid form with other impurities that have mixed with it .
STAGE THREE: CASTING STAGE: The hot molten (liquid) metalis poured into container of different lengths and sizes called moulds .it is left there to solidify to take up the shape of the mould, this is called casting. This is how round bars, square bar,wires and others are produced
Briefly explain the three stages of metal production.
METAL ALLOYS,EXAMPLES PROPERTIES, AND USES
An alloy is a metal that is obtained by mixing two or more metals together examples are ferrous alloys and non- ferrous alloys
High speed steel
Iron, carbon, vanadium and tungsten
Hard and brittle it will withstand temperatures up to 600 0C
Machine cutting tools such as drill bits.
Iron ,carbon, chromium and sometimes nickel
Hard and difficult towork,resist corrosion takes a high polish and will not rust.
Cutlery, hand cutting tools, washbasins
and sink containers for corrosives.
High tensile steel
Iron, carbon,nickel and chromium
Very strong and tough
Components where high strength is needed, engine parts, bolts and nuts for cars and machinery
NON FERROUS ALLOYS
Copper65%, zinc 35%
Can be bent and pressed into shapes, resist corrosion very well
Plumbing industry, ammunition(bullet and shell) Castings, wires rivets screws decorative works
4.5%copper, 0.5% manganese, 0.5% magnesium, and
It becomes hardened with age
It is used to make aircrafts and sheets
Copper 90%, zinc 10%
Very malleable and ductile, resist corrosion well
Decorative beaten work, cheap jewellery.
Strong and tough with high tensile strength, resist corrosion and machine well
Statues, ornaments, Bearings, springs electrical and architectural work.
Read about ‘processing clay, ceramics, plastics,rubber and glass
(i) EVANS Basic Technology for JSS book 3.
(ii) NERDC Basic Technology for JSS book 3.pg.22-36.
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