Classification of Materials

CHAPTER FOUR

Learning ObjectivesLearning Objectives

You will learn•about different kinds of materials• to distinguish between these materials in terms of their properties• to choose a material for a particular use

You will learn•about different kinds of materials• to distinguish between these materials in terms of their properties• to choose a material for a particular use

Examples of classification in our daily life.

•Books in the library•The items in the supermarket.•In “Maple Story”, all characters are

classified into warrior, magician, bowman or thief.

Different ways of classifying materialsDifferent ways of classifying materials

There are many ways of classifying e.g. Physical property.

Physical property is a characteristic of matter that can be observed without causing any change to the matter.

Examples: Colour, Size and Shape.

Physical PropertiesPhysical Properties

Other Physical properties that can be used to classify objects.

Other Physical properties that can be used to classify objects.

PropertiesProperties DefinitionsDefinitions

11 StrengthA material’s ability to support a heavy load without breaking or

tearing.

22 Density The mass in each unit of volume.

33 HardnessA material’s ability to withstand

wear and scratches.

44 FlexibilityA material’s ability to bend

without breaking and to return to its original shape.

55 Melting PointThe temperature of a substance at which it changes from a solid to a

liquid.

Physical PropertiesPhysical Properties

Other Physical properties that can be used to classify objects.

Other Physical properties that can be used to classify objects.

PropertiesProperties DefinitionsDefinitions

66 Boiling PointThe temperature of a

substance at which it changes from a liquid to a gas.

77Electrical

Conductivity

A measure of how readily electricity passes through a

substance.

88Heat/ thermal Conductivity

A measure of how readily heat passes through the substance.

More on StrengthMore on StrengthExamples of strong materials: Steel and concrete

Buildings and houses are make of steel and concrete to ensure that it does not collapse easily.

Pure metals are weak, they are made stronger by combining it with metal or non metal.

Iron are made stronger by combing it with carbon to form steel.

Examples of strong materials: Steel and concrete

Buildings and houses are make of steel and concrete to ensure that it does not collapse easily.

Pure metals are weak, they are made stronger by combining it with metal or non metal.

Iron are made stronger by combing it with carbon to form steel.

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More on DensityMore on Density

Density (kg/m3) =

Example: Aluminium (low density)

It is used in the manufacture of drink cans and body parts of airplane.

Density (kg/m3) =

Example: Aluminium (low density)

It is used in the manufacture of drink cans and body parts of airplane.

)(m Volume

(kg) Mass3

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More on HardnessMore on Hardness

The hardness of an object can be compared using a Moh’s scale.The hardness of an object can be compared using a Moh’s scale.

Hardness No.

11 22 33 66 77 1010

Materials

talc fingernail $1 coin steel quartz diamond

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More on FlexibilityMore on Flexibility

The picture below shows flexible curve which you use it to draw curves.

The insulation tubing for our cables and wires are very flexible too.

The picture below shows flexible curve which you use it to draw curves.

The insulation tubing for our cables and wires are very flexible too.

Flexible Curve Insulation tubing

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More on Melting Point and Boiling pointMore on Melting Point and Boiling point

The melting point and boiling point of water is 0°C and 100°C respectively.

Metals have high melting point and boiling point.

Ovenware is made of metals with high melting point, so as to withstand the high heat of oven.

The melting point and boiling point of water is 0°C and 100°C respectively.

Metals have high melting point and boiling point.

Ovenware is made of metals with high melting point, so as to withstand the high heat of oven.

OvenwareBack

More on Electrical ConductivityMore on Electrical Conductivity

Wires tubing have poor electrical conductivity (insulators).

Electrical wires are made of those with good electrical conductivity (conductors).

Wires tubing have poor electrical conductivity (insulators).

Electrical wires are made of those with good electrical conductivity (conductors).

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More on Heat ConductivityMore on Heat Conductivity

Styrofoam, plastics and wood are examples of poor conductors.

Metals are good conductors of heat.

Several kitchen wares are made of both heat insulators and conductors.

Styrofoam, plastics and wood are examples of poor conductors.

Metals are good conductors of heat.

Several kitchen wares are made of both heat insulators and conductors.

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Types of MaterialsTypes of Materials

A material is a substance used for making objects.

Materials can be classified into 5 main groups.

A material is a substance used for making objects.

Materials can be classified into 5 main groups.

fibresfibresmetalsmetals

MATTERMATTER

glassglassplasticsplastics ceramicsceramics

MetalsMetals

•Shiny•Flexible•Good conductors of heat and electricity•Can be bent and drawn into wires (ductile)•Can be beaten into different shapes without

breaking (malleable)•Some metals corrode easily while others do

not•High melting and boiling points

•Shiny•Flexible•Good conductors of heat and electricity•Can be bent and drawn into wires (ductile)•Can be beaten into different shapes without

breaking (malleable)•Some metals corrode easily while others do

not•High melting and boiling points

•Most are made from petroleum•Strong, but light•Do not corrode•Poor conductors of heat and electricity•Can be moulded into shapes•Low density•Flexible

•Most are made from petroleum•Strong, but light•Do not corrode•Poor conductors of heat and electricity•Can be moulded into shapes•Low density•Flexible

PlasticsPlastics

•Transparent•Brittle (easily broken)•Poor conductor of heat and electricity•Do not corrode•Can be moulded into shapes• Inflexible•High melting point

•Transparent•Brittle (easily broken)•Poor conductor of heat and electricity•Do not corrode•Can be moulded into shapes• Inflexible•High melting point

GlassGlass

•Non-metallic solids (eg. clay)•Hard, but brittle•High melting point•Poor conductors of heat and electricity•Do not corrode

•Non-metallic solids (eg. clay)•Hard, but brittle•High melting point•Poor conductors of heat and electricity•Do not corrode

CeramicsCeramics

•Flexible•Low Density•Poor conductors of heat and electricity•Soft - Can be spun into threads and

woven into fabrics•Can absorb dyes

•Flexible•Low Density•Poor conductors of heat and electricity•Soft - Can be spun into threads and

woven into fabrics•Can absorb dyes

FibresFibres

Properties and Uses of MaterialsProperties and Uses of Materials

The use of a material for making things depends on its properties.

Questions to be considered when choosing appropriate materials:

• should the material be strong?

• should the material be light?

• should it be attractive?

The use of a material for making things depends on its properties.

Questions to be considered when choosing appropriate materials:

• should the material be strong?

• should the material be light?

• should it be attractive?

Examples of five main groups of materials:Examples of five main groups of materials:

MetalsMetals

MaterialsMaterials UseUseReasons for Reasons for

Choosing the Choosing the MaterialMaterial

11

A drink can is made of aluminium

•strong•low density•does not

corrode easily

Electrical wires are

made from copper

•good conductor of electricity

•strong•does not

corrode

Gold jewellery

•shiny•does not

corrode

Examples of five main groups of materials:Examples of five main groups of materials:

MaterialsMaterials UseUseReasons for Reasons for

Choosing the Choosing the MaterialMaterial

22

Plastic bags

•lightweight (low density)

•flexible•strong

Plastic drink and

food containers

•lightweight•easily moulded•poor conductors

of heat

Electrical switch

•strong•does not conduct

electricity

PlasticsPlastics

Examples of five main groups of materials:Examples of five main groups of materials:

MaterialsMaterials UseUseReasons for Reasons for

Choosing the Choosing the MaterialMaterial

33

Window panes

•transparent•hard

Thin protective glass layer on metal

objects such as

refrigerators and baths

•hard (protects the metal)

•does not corrode

GlassGlass

Examples of five main groups of materials:Examples of five main groups of materials:

MaterialsMaterials UseUseReasons for Reasons for

Choosing the Choosing the MaterialMaterial

44

Porcelain plates

•poor conductor of heat (retains heat)

Cooking pots

•poor conductor of heat (retains heat)

•do not corrode•high melting point

CeramicsCeramics

Examples of five main groups of materials:Examples of five main groups of materials:

MaterialsMaterials UseUseReasons for Reasons for

Choosing the Choosing the MaterialMaterial

55

Cotton clothes

•lightweight•absorbs body

perspiration•able to absorb

dyes

Nylon (a plastic) fishing

line

•strong•flexible

FibresFibres

Scientists are developing many new kinds of ceramics with useful properties to replace other materials. Some of these are strong, light, durable, hard and do not corrode.

Examples include engine parts, artificial teeth and bones.

Scientists are developing many new kinds of ceramics with useful properties to replace other materials. Some of these are strong, light, durable, hard and do not corrode.

Examples include engine parts, artificial teeth and bones.

outer surface of space shuttle is covered with special heat resistant

ceramic tiles

outer surface of space shuttle is covered with special heat resistant

ceramic tiles

blades of these knives are made of special ceramics instead of steel

blades of these knives are made of special ceramics instead of steel