2. THE PROPERTIES OF METALS:
Hard
Non-adhesive
Cold and smooth
Often shiny
Vocabulary:
-Smooth: A surface that is not rough
-Shiny: reflects light of a smooth or polished surface
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3. PHYSICAL PROPERTIES:
Strong: Can resist forces while not becoming deformed easily.
Ex. Tensile…
Ductile and malleable: Can be made into wire or thin sheets.
Tough: Don’t break esaily.
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4. Electrical, thermal and acoustic conductivity: They’re
good conductors for electricity, heat and sound.
Magnetic: Magnets attracts some metals.
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5. Fusible: Can be easily welded to other metallic objects.
Expansion and contraction: When the temperature rises, they
expand and when it falls, they contract.
Plastic and elastic: Some metals are elastic, they can bend and
return to their original shape when they are affected by external
forces.
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6. CHEMICAL PROPERTIES:
Oxidation: React with oxygen
in water and air
ECOLOGICAL PROPERTIES:
Recyclable and reusable: Most metals are recyclabe:
when they have been used, they can be processed to be
used again.
Toxic: Some metals, such as lead or mercury, present a
danger to human beings and the environment.
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7. Where and how metals are obtained?
Metals are taken from minerals contained in rocks.
1-SURFACE MINING: is used when the mineral
layer is near the surface.
2-UNDERGROUND MINING: is used when the
mineral is deep below the surface.
1
2
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8. Ferrous materials
CHARACTERISTICS:
-Common.
-Inexpensive to extract.
-Need processing to produce pure iron.
-Used to make alloys.
ALLOY: is a mixture of two or more chemical elements
THERE ARE THREE TYPES OF ALLOYS:
1- Pure iron.
2- Steel.
3-Cast iron.
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9. Steel
Alloy steels
Silicon: makes the alloy
magnetic and improves elasticity.
Manganese: makes the alloy
harder and heat-resistant.
Nickel: improves strength
and prevens corrosion.
Tungsten: makes the steel harder,
more heat-resistant, and prevens corrosion.
Chrome: makes the alloy harder
and tougher and more rustproof.
Lead: makes it easier to cut steel with machine tools.
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10. -The steelmaking process
1- The iron mineral is washed to remove impurities.
2- It is crashed and sieved (the gangue is separeted from the ore)
3- The iron mineral (ore) is mixt with carbon and limestone.
4- This is smelted at a temperature of over 1500°C in a blast furnace.
5- Pig iron is obtained (molte iron mixt with carbon and impurities)
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11. HEAVY METALS
LEAD:
SOURCE
Galena
CHARACTERISTICS
USES
- Silvery grey
- Soft and malleable.
- Is very toxic when lead
fumes are inhaled.
Batteries, protective
measures against nuclear
radiation.
An additive in glass to give
hardness and add wight.
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12. Tin:
SOURCE
CHARACTERISTICS
USES
Casstierite
- Shiny white.
- Very soft.
- Does not oxidise at
room temperature.
Tin foil and tin plate (a
sheet of steel coated on
both sides with a thin
layer of tin).
Alloyed with lead, it is
used for soft soldering
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18. Shaping techniques
Powder metallurgy:
This progect have five states:
The metal is ground into powder.
It is pressed into steel dies.
It is heated to a temperature close to 70% of the metal’s
melting point.
Preassure is applied to produce the required dimensions.
The object is left to cool.
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19. Shaping techniques
Casting: used to change the dimensions of the object.
The metals is heated to the casting process
The liquid metal is poured into the mould
The mould and metal are left to cool until the metal has
solidified.
The solidified piece is extracted from the mould
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