Materials Flashcards
What sort of plastics can only be heated once?
Thermosetting plastics. These plastics undergo a chemical change change when heated and become hard and rigid.
Can thermosetting plastics be recycled?
No. thermosetting plastics cannot be recycled.
What are thermosetting plastics used for, because they resist heat so well?
Electrical fittings and pan handles. Also, any situation when the plastic needs to be very hard.
Examples of thermosetting plastics
Melamine-formaldehyde
Polyester resin
Epoxy resin
Urea-formaldehyde
What sort of plastics do not resist heat well - they can be melted and formed multiple times?
Thermoplastics can be melted and formed many times. When formed, they are also very bendy.
Are thermoplastics recyclable?
Yes. Thermoplastics can be melted down and reformed into a new product.
Examples of thermoplastics?
Acrylic ABS Polystyrene High Impact Polystyrene Polythene
Surface finishes for plastics?
Plastics don’t need protective surface finishes because they are very resist pant to corrosion and decay
Giving a plastic surface a nice appearance.
Wet and dry paper (silicon carbide).
Mild abrasive polish,
Anti-static cream,
Buffing machine.
Plastics are made from….
Crude oils. They are extracted from the ground then taken to a refinery. The oils are separated. Some are used to make plastics.
Ferrous metals contain….
Iron. They are often magnetic.
Properties of Mild Steel?
Strong and cheap. Rusts easily and can’t be hardened or tempered.
Uses of Mild Steel?
Car bodies, screws, nuts, bolts, nails, washing machines.
Properties of High-Carbon Steel?
Hard and can be hardened or tempered. Unfortunately, it is hard to work and rusts.
Properties of Stainless Steel?
Hard and doesn’t rust but is expensive
Uses of High-Carbon Steel?
Drills, files, chisels and saws
Use of Stainless Steel?
Medical Equipment, Sinks, Kettles, Cutlery
What’s a Non-Ferrous Metal?
Doesn’t contain iron.
Properties of Aluminium?
Lightweight and corrosion resistant. Expensive and not particularly strong.
Uses of Aluminium?
Aeroplanes, Cans, Ladders
Properties of Brass?
Quite strong, Corrosion-Resistant, Malleable, Ductile.
Properties of Copper?
Malleable, Ductile and conducts electricity well.
Uses of Copper?
Wiring, Pipes
Uses of Brass?
Door Handles, Electrical Parts
Common stock forms
Sheet, Strip, Tubing
2 composites?
Glass-reinforced plastic : boats, cars
Carbon fibre reinforced plastic : protective helmets, racing cars, bulletproof vests
Why might nano-materials be bad?
Harmful to environment and difficult/expensive to dispose of
What’s a smart material?
A smart material are materials that react to a stimuli in their environment.
What is annealing?
Metal is heated and left to cool slowly. This makes it softer, ductile and less brittle
What is hardening?
Metal is heated, then cooled rapidly. Heated then put in water to cool. This leaves metal brittle, so it is often tempered afterwards.
What is tempering?
Tempering makes metal tougher and less likely to break. It is done by gently heating the metal.
Explain plastic coating.
Metal is heated evenly then plunged into fluidised powder for a few seconds. Metal is put back into the oven and plastic fuses to it.
Recycling wood
Wood is either reclaimed or shredded to make playground flooring, chipboard or compost.
6 R’s of recycling
Repair Reuse Recycle Rethink Reduce Refuse
