materials
DESCRIPTION
Propiedades dos materiais para a sección bilingüe de tecnoloxíaTRANSCRIPT
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MaterialsTechnology, Xosé Rodríguez
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Properties of materialsToughness: a measure of the ability of a material to withstand a shock load.
Hardness: describes the ability of a material to withstand scratching.
Strength: the ability of a material to withstand being damaged.
Elasticity: the property of certain materials that enables them to return to their original dimensions after an applied load has been removed.
Plasticity: plastic materials will remain deformed even when the load has been removed.
Conductivity: a measure of the ability of a material to conduct heat or electricity.
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Plastics
1. Plastics are widely used in the home. There are many different types, some are hard, others are soft. Some are translucent, others are opaque. Propierties:
I. Very low electrical conductivityII. Low thermal conductivityIII. Low density, plastics are light.
2. There are two main groups:
I. Long chains of molecules make up thermoplastics. These can be softened with heat.
II. The molecules of thermosets interlock to form rigid materials which cannot be softened by heat.
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• Thermoplastics can be INJECTION MOULDED:This machine turns granules into molten
plastic.This is injected into a hot mould where it is cooled and solidified to form the required product.
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• Extrusion– Molten plastic is pushed
through a die to make long recular sections these are then cooled and solidified in a water bath.
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• Vacuum forming– Plastic sheet is heated when it is soft it is
sucked onto the mould by pumping ou the air form the mould chamber.
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Metals1. Propierties of metals
a. High electrical conductivity
b. High thermal conductivity
c. Though, hard and strenght.
Metals
FERROUSContain IRON
NON-FERROUSContain no IROn
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Ferrous metals
Wrought iron, it has a very low carbon content.
Steel is an alloy of iron and carbone with less than 2% of carbone.
Stainless steel, also known as inox steel or inox.
Cast iron is an alloy of iron and carbone with more than 2% of carbone.
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Wrought iron
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Steel
A steel pylon suspending overhead powerlines.
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Cast iron
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Non-ferrousCopper, malleable, ductil, good
conductor of heat and electricity.
1. Bronze, alloy copper with tin.
2. Brass, alloy copper with zinc: strong and ductile Copper
Bronze
Brass
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Non ferrous
• Aluminium:Light, ductile, soft,
high resistance to corrosion, silver colour
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Non ferrous
• Tin–Tinplate is sheet
steel covered with a thin layer of tin.
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Non-ferrous
• LeadBlue grey colour,
soft and very heavy.
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I will show you an image, and then you have to say the
propierty or material related
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Toughness,(fragile)
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Elasticity
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Strenght
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Hardness
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Wrought iron
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Aluminium
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Copper