properties of materials

• what materials are used for depends on their properties
• ceramics include glass and clay ceramics such as porcelain and bricks. They're insulators of heat and electricity, brittle and stiff
• polymers are insulators of heat and electricity and can be flexible. easily moulded. clothing, insulators in electrical items
• the properties of composites depend on the matrix/binder and the reinforcement used to make them, many different uses
• metals are malleable, good conductors of heat and electricity, ductile, shiny and stiff. electrical wires, cutlary
• alloy of iron called steels are used instead of pure iron. steels are made by adding small amounts of carbon and sometimes other metals to carbon.
• low carbon steel - easily shaped, car bodies
• high - carbon steel - very strong, inflexible, brittle. bridges
• stainless steel - corrosion resistant, hard. cutlery
• bronze = copper + tin. bronze if harder than copper. used for medals
• brass = copper +zinc. brass is more malleable than bronze, used when lower friction is needed
• gold alloys used to make jewellery. pure gold is soft. metals are used to harden the gold.
• aluminium alloys are used to make aircraft. low density, pure aluminium is too soft for aeroplanes so alloyed with small amounts of other metals to make it stronger