Polymers, alloys, composites and ceramics

• What is bronze an alloy of? What can it be used for?

  Bronze is an alloy of copper and tin. It can be used for statues, bells and coins.
• What is brass an alloy of? What can it be used for?

  Brass is an alloy of copper and zinc. It can be used for musical instruments, door knobs and hinges.
• When used as jewellery, what is gold usually alloyed with?

  Silver, copper or zinc.
• How many carats is pure gold?

  24 carats
• How many carats is 50% gold?

  12 carats
• What is the proportion of gold in 6 carat gold?

  25%
• Why is gold alloyed to make jewellery?

  It makes the jewellery harder and less expensive.
• What are steels?

  Alloys of iron that contain specific amounts of carbon and other metals.
• Properties of high carbon steel

  strong but brittle
• Properties of low carbon steel

  softer and more easily shaped
• Properties of stainless steels (containing chromium and nickel)

  hard and resistant to corrosion
• Properties of aluminium alloy

  Low density
• Uses of 4 alloys: high, low carbon, stainless steel and aluminium

  Aluminium - drinks can, easily collapsed for recycling

  Stainless steel - cooking pans washed on a daily basis

  High carbon steel - masonry nails driven into concrete without bending

  Low carbon steel - pipes which need to be the same shape and size
• How is soda-lime glass made?

  By heating a mixture of sand, sodium carbonate and limestone
• How is borosilicate glass made?

  Made from sand and boron trioxide and melts at higher temperatures than soda-lime glass.
• How are bricks and pottery made?

  Made by shaping wet clay then heating in a furnace.
• Why do polymers have different properties?

  Properties depend on what monomers they are made from and the conditions under which they are made e.g. LD and HD poly(ethene)
• Difference between thermosoftening and thermosetting plastics


  Thermosoftening plastics melt when they are heated, whereas thermosetting plastics do not melt when they are heated due to them having crosslinks
• What is a composite?

  A product made from 2 materials that have improved properties:

  • a matrix that holds together other fragments (reinforcement)
• Give 2 examples of composites

  Fibreglass: glass fibres (reinforcement) and polymer resin (matrix)

  Chipboard: wood chip (reinforcement) and resin glue (matrix)