Using resources Flashcards
what are ceramics
non metallic solids with high melting points that are not made from carbon based compounds
what are some general properties of ceramics
good insulators of heat and electrify and very brittle and stiff
what are clay ceramics
when clay is fired at a high temperature it hardens to form a cay ceramic. Ideal for making pottery and bricks
what are glass ceramics
glass can be moulded when hot and brittle when thin.
most glass is a soda lime glass ( made by heating limestone, sand and sodium carbonate until it melts and then it cools to become glass.
borosilicate glass has a higher melting point. its made in the same way as soda lime glass but using sand and boron trioxide
what are composites
one material embedded in another. fibres or fragments are surrounded by a matrix which acts as a binder
what are polymers
large molecules formed when small molecules ( monomers) join together.
held by strong covalent bonds in long chains
most insulators of heat and electricity and can be flexible
clothing, insulators and electrical items
what are two important things that influence the properties of a polymer
the monomers
conditions in which its made
how do the monomers effect the property of a polymer
they determine what type of force form between the polymer chains. e.g. if there are cross links or not
what are thermosoftening polymers
made of individual tangled chains of polymers. weak forces between the chains which mean they are flexible and can be melted and remoulded.
what are thermosetting polymers
cross links between polymer chains so doesn’t melt when heated, it chars instead. They are strong, hard and rigid
how do reaction conditions affect the properties of polymers
low density polyethene is made at 200 degrees under hp.
high density polyethene is made at a lower temp and pressure with a catalyst
what are alloys
mixtures of two or more metals or a metal and non metal
why do we use a lot of alloys
pure metals are often too soft because the layers of atoms slide over each other
why are alloys harder than most metals
different elements have different sized atoms so it will distort the layers of the metal atom making it harder for the layers to slide
why is most iron used to make steel
too soft and bendy
what is added to iron to make steel
carbon and sometimes other metals
give a use for both low carbon and high carbon steel
low - car bodies
high- bridges
what is added to make stainless steel
chromium and sometimes nickel
bronze
idk but i should
brass
alloy of copper and zinc gold like appearance more malleable than bronze good for application which require moving with low friction e.g. water taps and door fittings
gold alloys
used for jewellery cus pure gold is too soft
zinc, copper and silver can be used to harden gold
have slightly different colour to pure gold
aluminium alloys
low density
aircrafts
alloyed with small amounts of other metals to make it stronger as its too soft for aeroplanes
what is corrosion
when a metal is gradually destroyed by reacting with substances in the environment
what is the equation for iron rusting
iron + oxygen + water makes hydrated iron (iii) oxide
when aluminium corrodes, why doesn’t it get completely destroyed
the aluminium oxide doesn’t flake away so it leaves a protective layer
how do you experiment rusting
nail in boiling tube w water and it wont rust
just air it wont rust
water and air it will rust
how can creating a barrier prevent rust
painting a metal or coating w plastic
electroplating uses electrolysis to reduce metal ions onto an iron electrode. can be used to coat iron with a different metal that wont corrode
oiling or greasing
how can the sacrificial method be used to prevent rust
put more reactive metal w the one u want to protect so reaction will take place w that one