1Ceramics are brittle
Ceramics, like china, tiles and glass, are hard but brittle: a sharp blow shatters them. Metals dent and polymers bend.
ceramicbrittle
Lesson 23.3 notes
Ceramics, polymers and composites
Three families of materials and their properties: hit them, heat them, bend them and test them.
2Ceramics take the heat
Ceramics have very high melting points and don't burn, so they line kilns and furnaces. They are good insulators of heat and electricity.
insulator
3Polymers are chains
A polymer is a very long chain made of thousands of small molecules called monomers, joined end to end.
polymermonomer
4Polymers soften when heated
Most plastics soften when heated and harden again as they cool, so they can be moulded into shape.
plastic
5Polymers insulate
Polymers such as PVC are flexible electrical insulators, so they are used to cover wires.
6Composites
A composite combines two materials. Concrete is strong when squashed but cracks when stretched; steel bars inside it take the stretching.
composite
7Strong and light
Carbon fibre is strong carbon fibres set in a polymer. It is as strong as steel but much lighter.
carbon fibre
Explore: Materials test bench
Choose a material and a test: hit it, heat it, bend it, or put it in a circuit. Fill in the table and compare the families.
Common mistake: A composite is more than a mixture
In a composite, two materials are combined so that each does a job. In reinforced concrete, the concrete resists squashing and the steel bars resist stretching.
Remember
- Ceramics, like pottery, brick and glass, are hard, brittle, heat-resistant electrical insulators.
- Polymers are long chains of small molecules (monomers). Most are flexible, light, insulating, and soften when heated.
- Composites combine two materials to get the best of both, like reinforced concrete and carbon fibre.
Going further at GCSE