Using resources Flashcards
What are ceramics?
Non metals with high melting points
Some are made from clay and when hardened form cermaics
Made for pottery and bricks
Can be glass too
Difference between soda lime glass and brosocilate glass?
Soda lime glass is made from sodium, limestone and sand
Brosocilate glass is made from sand and boron trioxide
What is a polymer?
They have different properties depending on what its made from and how it is made.
Polyethene is flexible when made at a moderate temp and high pressure
Polyethene is rigid when made with low temp and with a catalyst
What is a composite?
A material embedded in another
The fibres or fragments of a material are surrounded by a matrix acting as a binder
Examples of composites?
Fibre glass - Made from fibres of glass embedded in a matrix of plastic. Low density but very strong
Carbon fibre - Made from long chain carbons or carbon nanotubes embedded in platic matrix. Strong and light
Concrete - Made from sand gravel embedded in cement. Very strong
Examples of natural composite?
Wood is a natural composite made from cellulose fibres
What is a thermosoftening polymer?
They contain individual polymer chains entwind together with weak forces
They are meltable amd mouldable
What is a thermosetting polymer?
They contain monomers with cross links
They are very hard and dont soften
What is an alloy?
A pure metal combined with another element
This makes them harder
An example of an alloy?
Brozne - copper + tin
Brass - Copper + Zinc
What is meant by carat?
Gold is made up of 24 carats
So if gold is said to be 18 carats then it is 75% pure
What is corrosion of metals?
Metals that weaken when reacted with the environments
How does iron rust?
When in contact with water and air
Rust flakes away
How does aluminum rust?
When in contact with only air
It doesnt flake away only forms a protective later of aluminum oxide on top
How can rusting be prevented?
Coating iron with a barrier:
* Painting with plastic
* Electroplating with electrolysis to reduce metal ions
* Oiling or greasing
Sacrifical method
* Placing metal with a more reactive metal like `inc so the more reactive metal oxidises instead