4.10.3 - Using materials

Corrosion definition.(+ example)

The destruction of materials by chemical reactions with substances in the environment. E.g. Rusting of iron due to exposure to water and air.

How can corrosion be prevented?

Applying a coat of paint, grease or electroplating.

applying a coating with a more reactive metal (zinc) as a sacrificial metal.

Investigate the conditions for rusting.

Water and Oxygen needs to be available to form a hydrated iron oxide.

What is an alloy?

A mixture of two or more metals.

What metals make up Bronze?

Copper and Tin.

What metals make up Brass?

Copper and zinc.

What metals make up Steel?

Iron and Carbon. (high amount of carbon means the steel is brittle)

What is Bronze used for?

statues, bells, coins.

What is Brass used for?

musical instruments, door knobs, locks and taps.

What is Gold used for?

jewellery (24 carats is 100% gold)

What is Steel used for?

cars, because when it contains a low proportion of carbon it is soft and malleable.

How is soda-lime glass made?

Heating a mixture of sand, sodium carbonate and limestone.

How is borosilicate glass made?

Heating sand and boron trioxide, melts at higher temps that soda-lime glass.

What is a polymer?

A long chain made from smaller molecules.

What is a monomer?

The small molecules that make up polymers.

What are thermosoftening polymers?

Polymers that melt and become softer when heated.

What are thermosetting polymers?

They become rigid when heated, they don’t melt.

Explain how low density and high density poly(ethene) are produced from ethene.

Ethene is the monomer which produces boths polymers, Low density poly(ethen) has a branched structure, meaning the ethene molecules are arranged randomly. High density poly(ethen) has less/no branching of polymer chains, so the molecules are lined up closer together.

explain the difference between thermosoftening and thermosetting polymers in terms of their structures.

Thermosoftening polymers are made up of individual, tangled polymer chains and easily when they are heated. Thermosetting polymers consist of polymer chains with strong cross-links so they do not melt when heated.

What is the reinforcement of two materials?

When a matrix or binder, surround and bind fibres together or fragments of materials.

Name four composite materials, their reinforcement and matrix.

Reinforced concrete - steel - concrete

Fibreglass - Glass fibre - Polymer resin

Carbon fibre reinforced polymer - carbon fibres - polymer resin

Chipboard - wood chips - resin glue.