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Ceramics, polymers and composites
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Engineers choose materials by their properties. Ceramics, polymers and composites each have their own strengths.
Ceramics
Ceramics include pottery, brick, china and glass. They are made by heating materials such as clay or sand to high temperatures.
Properties: hard, brittle (they shatter), high melting points, and good insulators of heat and electricity.
Uses: plates, tiles, bricks, insulators on electricity pylons.
Properties: hard, brittle (they shatter), high melting points, and good insulators of heat and electricity.
Uses: plates, tiles, bricks, insulators on electricity pylons.
Polymers
Polymers are made of very long chain molecules. Most plastics are polymers, such as poly(ethene) and PVC.
Properties: usually low density, flexible or easily shaped, electrical insulators, waterproof.
Many do not biodegrade, so waste plastic can last for hundreds of years.
Properties: usually low density, flexible or easily shaped, electrical insulators, waterproof.
Many do not biodegrade, so waste plastic can last for hundreds of years.
Composites
A composite is made of two or more materials combined, giving better properties than either alone.
Reinforced concrete: concrete is strong when squashed; steel rods inside make it strong when stretched too.
Fibreglass (glass fibres in a polymer) and carbon fibre are strong but light, used in boats, bikes and racing cars.
Reinforced concrete: concrete is strong when squashed; steel rods inside make it strong when stretched too.
Fibreglass (glass fibres in a polymer) and carbon fibre are strong but light, used in boats, bikes and racing cars.
Why is a ceramic used for the insulators that hold power cables on pylons?
- The insulator must stop electricity flowing into the pylon.
- Ceramics are very good electrical insulators.
- They are also hard and do not rot or melt in hot weather.
Answer: Ceramics are excellent electrical insulators and are hard and long-lasting.
Ceramics: hard, brittle, high melting point, insulators. Polymers: long chains, low density, flexible, insulators, often do not biodegrade. Composites combine materials to get the best of both, like reinforced concrete and carbon fibre.
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