metals
DESCRIPTION
TRANSCRIPT
MetalsBy: Ariadna Riera,
Maria LorenzoAnd
Marcel Sales
Marcel
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
Ari
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. Maria
Electrical, thermal and acoustic conductivity: They’re good conductors for electricity, heat and sound.
Magnetic: Magnets attracts some metals.
Marcel
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. Ari
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.
Maria
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
Marcel
Ferrous materialsCHARACTERISTICS:
-Common.
-Inexpensive to extract.-Need processing to produce pure iron.-Used to make alloys.
ALLOY: is a mixture of two or more chemical elementsTHERE ARE THREE TYPES OF ALLOYS:
1- Pure iron.2- Steel.3-Cast iron.
Ari
SteelAlloy 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 harderand tougher and more rustproof.Lead: makes it easier to cut steel with machine
tools.Maria
-The steelmaking process1- 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)
Marcel
HEAVY METALS LEAD:
SOURCE CHARACTERISTICS USES
Galena
- 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.
Ari
Tin:SOURCE CHARACTERISTIC
SUSES
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
Maria
Zinc:SOURCE CHARACTERISTICS USES
Sphalerite and hemimorphite
-Bluish grey-Shiny-Weak at low temperatures-Not very hard
Roofing, plumbing and in the car industry. A layer of zinc is used on other materials to stop corrosion
Marcel
Cooper:SOURCE CHARACTERISTICS USES
Cuprite, chalcopyrite and malachite
-Corrodes of oxidises very easly
Electrical wire, telephone lines, pipes, radiators, as decoration and in architecture jewellery and handicrafts
Ari
Bronze:SOURCE CHARACTERISTICS USES
Alloy cooper and tin -Resistant to wear and corrosion
Boat propellers, filters, church bells, sculptures, nuts, bearings and cogs.
Maria
Brass:SOURCE CHARACTERISTICS USES
Alloy cooper and zinc -Very resistant to corrosion
Handcrafts, jewellery, plumbing, capacitors and turbines
Marcel
Shaping techniquesShaping:
Rolling
Extrusion
Forging
Press forging
Punching
Bending
Wire drawingAri
Shaping techniquesPowder 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’smelting point.Preassure is applied to produce the required
dimensions.The object is left to cool.
Maria
Shaping techniquesCasting: used to change the dimensions of
the object.The metals is heated to the casting processThe liquid metal is poured into the mouldThe mould and metal are left to cool until the
metal has solidified.The solidified piece is extracted from the
mould
Marcel
Permanent joinRivet
Press fit join
Adhesive
Welding and soldering
Ari
Temporary joinsNuts and bolts
Screws
Threated stay bolts
Keyed joints
Splined shafts
Sliding joinsMaria
FinishiesFinishing is for:
Removing surface imperfectionsPolishingProtecting metals from water and corrosion
Finishing techniques:GrindingLappingPolishingBuffingCoatings
Marcel