UNIT 4 MATERIALS

Focus: Materials and their properties.

Grammar focus: The Participle.

Skills focus: Reading for specific information to know about materials and their properties, learning basic vocabulary and developing speaking skills.

1 .What materials have these properties?

1 soft 6 conductive

2 ductile 7 durable and hard

3 malleable 8 stiff and brittle

4 tough 9 corrosion-resistant

5 scratch-resistant 10 heat-resistant

Materials	Properties	Uses
1 Aluminium	Easy to shape, light, soft highly conductive, corrosion-resistant.	Aircraft, engine components, cooking foil, cooking utensils.
2 Copper	Very malleable, tough and ductile, highly conductive, corrosion-resistant.	Electric wiring, tubing.
3 Brass	Very corrosion-resistant(65% copper,35% zinc) Casts well, easily machined.Good conductor.	Valves, taps, castings, ship fittings, electrical contacts.
4 Mild steel (iron with 0.15% to0.3% carbon)	High strength, ductile, tough, fairly malleable. Cannot be hardened. Low cost. Poor corrosion resistance.	General purpose.
5 High carbon steel(iron with 0.7% to 1.4% carbon)	Hardest of the carbon steels but less ductile and malleable Can be hardened.	Cutting tools such as drills, files, saws.
6 ABS	High impact strength and toughness, scratch-resistant, light and durable. Easy to shape.	Safety helmets, car components, telephones, kitchenware.
7 Acrylic	Stiff, hard, very durable, can be polished easily, easy to shape	Aircraft canopies, baths, double glazing.
8 Diamond	Hardest natural material, can cut glass and metal.	Industrial cutting and grinding.
9 Glass	Clear, hard, breaks easily	Windows, bottles.
10 Optical fibre	Carries light and coded messages.	Lighting, cable TV, telecommunications.

2. Scan the table to find:

1 a metal used to make aircraft

2 a material used to cut hard substances

3 steel which can be hardened

4 an alloy suitable for castings

5 a material which can carry signals more efficiently than copper cables

6 a material suitable for safety helmets

7 a metal suitable for salt-water environment

8 a metal for general construction use but which should be protected from corrosion

9 a material which is transparent and breaks easily

10 a thermoplastic which can be polished and formed easily.

3. What are the objects around you made of/from?

Use Passive Voice: to be + Past Participle.

Do not confuse “made of” and “made from”. “Made of X“ implies that

the X is still (visibly) present.

4. Study these facts about aluminium:

Aluminium is a light metal.

Aluminium is used to make aircraft.

We can link these facts to make a definition of aluminium.

Aluminium is a light metal which is used to make aircraft.

Make definitions of each of the materials in column A. Choose the correct information in columns B and C to describe the materials in column A.

A	B	C
1 An alloy		allows heat or current to flow easily
2 Mild steel		consists of copper and zinc
3 A conductor		does not allow heat or current to flow easily
4 An insulator	a metal	contains iron and 0.7% to 1.4% carbon
5 High carbon steel	a material	becomes plastic when heated
6 Brass	an alloy	contains iron and 0.15% to 0.3% carbon
7 Optical fibres		formed by mixing other metals or elements
8 A thermoplastic		mixed with water (it) dries to a hard material
9 Cement		made from glass and are usually about 120 micrometres in diameter

5. Read the text and answer the questions after it.

COMPOSITE MATERIALS