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Raw materials are materials taken directly from nature that we process into other materials to make products with.

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We prepare or refine raw materials to obtain natural materials

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When we process raw materials,they become processed material (also called manufactured materials).

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Any material use to construct an object is called a technical material.

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Animals: wool,silk
Plants: linen,cork
Minerals: marble,clay,sand

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sheep-wool-scarf
rock-marble-furniture
rock-clay-bricks
plant-cotton-clothes
spider-silk-clothes

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An umbrella: cheap
A chair: strong
Frying pan: cheap and strong

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Each material has certain characteristics or properties that make it suited to a certain use.

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Plastic or wood chair: ·Advantages:
-Its cheaper
-Combine well with the decoration
-They are comfortable
-It is made with a waterproof material
-They are light
-They are strong and durable

·Disadvantage:
-It cab be broken more easily
-They damage nature

A earring out of silver or aluminium:
·Advantages:
-Decorate the ears
-Its good for our health

·Disadvantages
-There may be infections in the holes because there are people who have silver allergies

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Shoe: strong and attractive
Partition wall: can build with and strong
Streetlight: strong
Stay cables: cheap and avaliable

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Natural materials: slik,slate
Processed materials: latex,cork,lycra,brass

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Car headlight: strong, transparent
A mattress: nice to touch,soft
Golf Club: strong,hardness

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Man-made wood:
-Plywood
-Chipboard

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-Tensile strength: It is good in the longitudinal direction and poor in the transverse direction.
-Comprensive strength: It is better in the transverse direction than in the longitudinal direction.
-Flexural strength: It is good, but better in the transverse direction.
-Hardness: This can vary a lot. It depends on the type of wood,the structure and the cutting direction.Wood is not very hard and this makes it easier to work with.
-Toughness: Wood is tough,so is used in sports equipments.
-Thermal and electrical conductivity: It is very low.Wood is a good insulator of heat and electricity.
-Sound conductivity: Is good.This is why it is used as a material to make certain musical instruments.
-Colour: Different woods have different colours.The latter types of wood are prized for making furniture,woods with less interesting colours are used in construction.
-Density: Wood is a light material. It has a lower density than water,which means that it floats.

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Wood has several properties that are undesirable in technical applications:
-Combustion
-Moisture
-Rotting and insect attack

Exercise 11 pg 80
We can use wood as a technical material because is a thermal conductor,it is not hard and is light.But wood is not flexible and it can break easily

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Stock forms of metal
-Plates
-Sections
-Ingots

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Mechanical properties:
-They are hard
-Some are malleable
-Some are ductile
-They are tough
Thermal properties:
-They are very good conductors of heat
-They expand when the temperature rises and contract  when it falls.
-Some metals can be easily soldered.
Electrical and magnetic properties:
-They are very good conductors of electric current.
-Some have a magnetic behaviour and can attract other metals.

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Wood derivates:
-Paper
-Cardboard
-Cork

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Classifying  metals: Metals that contain mainly iron are called ferrous metals.Metals that do not have iron in their composition are called non-ferrous metals.

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Iron: When the percentege of carbon in the alloy is less than 0.1%, we call this material iron.
Steel: Steel is a ferrous material made mainly from iron with 0.1% to 2% carbon.
Cast iron: Cast iron is made from iron and 2% to 6.67% carbon.

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Copper: This is a bright red-coloured metal that has been used since ancient times.
Tin: Is a silver-coloured shiny metal that is very resistant to corrosion.
Aluminium: Is the third most common element is the earth crust. It is white,shiny,cheap and easy to recycle.
Zinc: It is bluishwhite in colour and is one of the least common metals.

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Natural woods: pine, ebony, beech,,ash,fir and lime.
Man-made woods: plywood and chipboard
Wood derivatives: paper,cork and carboard.

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To make a statue I would use bronze because is strong.

To make a sardine tin I would use tin because is not toxic.

To make wires I would use copper because is a good conductor of electricity.

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The metal that we can find in a oca-cola can and a Boeing is the aluminium.

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Steel is tougher than cast iron.