2. THE PROPERTIES OF METALS:
โช Hard
โช Non-adhesive
Cold and smooth
โช Often shiny
Vocabulary:
-Smooth: A surface that is not rough
-Shiny: reflects light of a smooth or polished surface
3. โซ PHYSICAL PROPERTIES:
โซ Strong: Can resist forceswhile not becoming deformed easily.
Ex. Tensileโฆ
โซ Ductileand malleable: Can be made intowire or thin sheets.
โซ Tough: Donโt break esaily.
4. โซElectrical, thermal and acoustic conductivity: Theyโre
good conductors forelectricity, heatand sound.
โซMagnetic: Magnets attracts some metals.
5. โซ Fusible: Can beeasilywelded toother metallicobjects.
โซ Expansionand contraction: When the temperature rises, they
expand and when it falls, they contract.
โซ Plastic and elastic: Some metals are elastic, they can bend and
return to theiroriginal shapewhen they areaffected by external
forces.
6. โซCHEMICAL PROPERTIES:
โซOxidation: Reactwith oxygen
in waterand air
โซECOLOGICAL PROPERTIES:
โซRecyclable and reusable: Most metals are recyclabe:
when they have been used, theycan be processed to be
used again.
โซToxic: Some metals, such as lead or mercury, present a
danger to human beings and the environment.
7. WHERE AND HOW METALS ARE
OBTAINED?
1
Metalsare 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.
2
9. STEEL
โซAlloysteels
โซSilicon: makes the alloy
magnetic and improveselasticity.
โซManganese: makes thealloy
harderand heat-resistant.
โซNickel: improves strength
and prevens corrosion.
โซTungsten: makes the steel harder,
more heat-resistant, and prevens corrosion.
โซChrome: makes thealloy harder
and tougherand more rustproof.
โซLead: makes iteasier tocut steel with machine tools.
10. -THE STEELMAKING PROCESS
โซ 1- The iron mineral is washed toremove impurities.
โซ 2- It is crashed and sieved (thegangue is separeted from the ore)
โซ 3- The iron mineral (ore) is mixt with carbon and limestone.
โซ 4- This is smelted ata temperatureof over 1500ยฐC in a blast furnace.
โซ 5- Pig iron is obtained (molte iron mixt with carbon and impurities)
11. HEAVY
METALS
โซLEAD:
SOURCE CHARACTERISTICS USES
Galena
- Silverygrey
- Soft and malleable.
- Isvery toxic when lead
fumes are inhaled.
Batteries, protective
measures against nuclear
radiation.
An additive in glass togive
hardnessand add wight.
12. โซTin:
SOURCE CHARACTERISTICS USES
Casstierite - Shiny white.
- Verysoft.
- Does not oxidise at
room temperature.
Tin foil and tin plate (a
sheetof steel coated on
both sides with a thin
layerof tin).
Alloyed with lead, it is
used forsoft soldering
13. โซZinc:
SOURCE CHARACTERISTICS USES
Sphaleriteand -Bluish grey Roofing, plumbing and in the
hemimorphite -Shiny car industry
. A layerof zinc is
-Weak at low used on other materials to
temperatures stopcorrosion
-Notvery hard
14. โซCooper:
SOURCE CHARACTERISTICS USES
Cuprite, chalcopyrite and -Corrodes of oxidises very Electrical wire,
malachite easly telephone lines,
pipes, radiators, as
decoration and in
architecture jewellery
and handicrafts
18. SHAPINGTECHNIQUES
โซPowder metallurgy:
This progect have five states:
โซThe metal is ground into powder.
โซIt is pressed into steel dies.
โซIt is heated to a temperatureclose to 70% of the metalโs
melting point.
โซPreassure isapplied to produce the required dimensions.
โซTheobject is left tocool.
19. SHAPINGTECHNIQUES
โซCasting: used tochange the dimensions of the object.
โซThe metals is heated to the casting process
โซThe liquid metal is poured into the mould
โซThe mould and metal are left tocool until the metal has
solidified.
โซThe solidified piece is extracted from the mould
