10.1 - Using Materials

• What are ceramics?

  Ceramics are non-metallic solids with high melting points that aren't made from carbon-based compounds.

  • Excellent insulators for heat and electricity
  • very brittle
  • stiff
• What are the 2 types of ceramics?

  Clay and glass
• What are clay ceramics?

  Clay is a soft material when it is dug up from the ground, so it can be moulded into different shapes. When it is fired at high temperatures, it hardens to form a clay ceramic. Ideal for making pottery and bricks.
• What are glass ceramics?

  Glass is generally transparent, can be moulded when hot and can be brittle when thin. Most glass is soda-lime glass - made by heating a mixture of limestone, sand an sodium carbonate. When it cools, it comes out as glass.
• What are composites?

  Composites are made out of one material embedded in another. Fibres or fragments of a material are surrounded by a matrix as a binder.

  
• Examples of composites:

  • wood
  • fibreglass
  • carbon fibre
  • concrete
• What are polymers?

  Polymers are very large molecules formed when many small molecules (called monomers) join together. Strong covelant bonds hold the atoms together in long chains.

  • Insulator of heat and electricity
  • flexible
  • easily moulded
  • used for clothing
• The monomers a polymer is made from determine what type of forces form between polymer chains. The forces between the chains have a large impact on the properties of a polymer.
• Thermo-softening polymers are made of individual tangled chains of polymers. There are weak forces between chains, meaning they are flexible and can be melted then re-moulded.
• Thermo-setting polymers have cross-links between their polymer chains. Meaning the polymer doesn't melt when it's heated. When it reaches a certain temperature, it just chars instead. Thermo-setting polymers are strong, hard and rigid.
• Identify the type of thermo-polymer:

  A) thermosetting

  
• Identify the type of thermo-polymer:

  A) thermosoftening

  
• Properties of metals:

  • good conductors of heat and electricity
  • malleable
  • ductile
  • shiny
  • stiff
• What is an alloy?

  Alloys are mixtures of two or more metals, or a mixture of a metal and a non-metal. Most metals used today and alloys.
• Pure metals are mostly too soft for many uses, as the layers of atoms slide over each other.
• Alloys are harder than pure metals, because they're made up of different sized atoms, so the layers are distorted and it is difficult to slide over each other.
• How is steel formed?

  Adding small amounts of carbon, and sometimes other metals, to the iron.
• What are the types of steel and their uses:

  • low-carbon steel - easily shaped - car bodies
  • high-carbon steel - strong, inflexible, brittle - blades, bridges
  • stainless steel - corrosion resistant, hard - cutlery, containers
• Common alloys:

  • bronze - copper and tin - statues, medals, decorative objects
  • brass - copper and zinc - water taps, door fittings
  • aluminium - other metals - aircraft
• Gold alloys:

  • make jewellery, pure gold is too soft
  • zinc, copper and silver are mixed with gold