Alloys Flashcards
Alloy
Mixture of elements which are harder than pure metals.
Bronze
- Alloy of copper and tin
- Extremely hard, and doesn’t corrode
- USED FOR STATUES
Brass
- Allow of COPPER and ZINC
- Hard, but can be formed into different shapes
- INSTRUMENTS, DOOR HANDLES
Gold
Usually Alloyed with :
- Silver
- Copper
- Zinc
To make it harder.
Purity of Gold is measured in KARATS
Steel
Alloys of Iron
- Contains specific amounts of the non-metal CARBON
- Steel also contains other metals
- High carbon steel is extremely hard but also brittle
- Tends to break if hit with hammer
- Cutting tools, CHISSELS
LOW CARBON STEEL
- Softer, more easily shaped, used to make CAR BODIES
Problem
- Can rust
- But to prevent it, there is STAINLESS STEEL
STainless steel
- Contains CHROMIUM and NICKEL
- Prevents rusting, and resists to corrosion and is HARD
Aluminium alloys
- Low density
- Makes them extremely useful in aeroplane bodies
Glass
Most of the glass which we use is called Soda-lime glass
By heating a mixture of sand, sodium carbonate and limestone, we form soda-lime glass
Borosilicate glass, made from sand and boron TRIOXIDE, melts at higher temperatures than soda-lime glass
WINDOWS AND BOTTLES
Relatively low melting point, which limits its uses
Clay ceramics
- Clay is a mineral found in the ground
- When it is wet, it can be shaped and then heated in a furnace to harden
Composites
Can be made when combining 2 different materials
REINFORCEMENT
- Consists of fibres or fragments of one material
MATRIX
- surrounds the reinforcement, a different material
They have different properties to the materials in them.
CARBON FIBRE
- Fibres of carbon are the REINFORCEMENT
- Matric is a PLASTIC RESIN
Very light, so useful in cars or aircraft parts
REINFORCED CONCRETE
- Steel Bars (REINFORCEMENT)
- Concrete (MATRIX)
Extremely strong so used to make buildings
Polymers
Properties of monomers depend on both the monomer and the conditions used to make the polymer
LDPE
- Softer
HDPE
- Harder
-
What can we change about he production of a polymer?
- Temperature
- Pressure
- Catalyst
Thermosoftening polymers
- They MELT when we heat them
- We can RESHAPE them while they are soft
- They then go back to a SOLID when they are cooled
- Polymer chains are held to each other by intermolecular forces
- On heating, the intermolecular forces break, now the polymer strands can separate from each other as the polymer melts
Thermosetting polymers
- Do not melt when heated
- Polymers are connected to each other by strong crosslinks
- The strong crosslinks are not broken by heat, which is why thermosetting polymers do not melt on heating
