Materials Flashcards
What are ceramics?
Non-metal solids with high melting points that aren’t made from carbon-based compounds
Clay ceramics
- soft material when dug up, can be moulded into many shapes
- hard when fired at high temperatures
- ideal for pottery and bricks
Glass ceramics
- transparent, moulded when hot, brittle when fin
- most from limestone, sand and sodium carbonate (soda-lime glass)
- Borosilicate is sand and boron trioxide, higher mp
Compositions
One material embedded in another.
Matrix and reinforcement
Fibreglass
Carbon fibre
Glass in polymer (plastic), low density, strong e.g. skis, boats
Reinforcement from long chains of carbon atoms or nanotubes, strong and light, aerospace and sports car
Concrete
Wood
Aggregate (sand+gravel) in cement- strong, building material
Cellulose fibres held together by an organic polymer matrix
What influences the properties of a polymer?
How it’s made, what it’s made from
Low and high density poly(ethene)
Low- moderate temperature, high pressure, flexible e.g. bags and bottles
High- lower temp and pressure, different catalyst, more rigid e.g. water tanks
Thermosoftening/setting polymers
Softening have weak forces and can be melted and remoulded
Setting form cross-links holding them together in a solid structure, don’t soften when heated
CROSS-LINKS AND STRONG COVALENT BONDS MAKE IT SET
Ceramic
e.g. glass, porcelain, bricks
Insulators, brittle, stiff
Polymers
Insulators, flexible, easily moulded
e.g. clothing, electrical insulators
Metals
Malleable, good conductors, ductile (can be drawn into wires), shiny, stiff
e.g. wires, car bodywork, cutlery
Bronze
Copper+tin
Harder than copper e.g. medals, statues
Brass
Copper+zinc
More malleable than bronze e.g. taps
Gold alloys
e.g. jewellery
Whatever the percentage out of 24 parts are gold is the purity
