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