3.5.7 - Iron, Steel And Other Metals Flashcards
What is rusting !?
. Rusting is the chemical process by which iron is oxidised to form rust
What is the chemical name for rust !?
. Hydrated iron (III) oxide
What two substances are required to form rust!?
. Oxygen
. Water
How many stages are there to rusting!?
. It happens in two stages
What is the FIRST stage of rusting ?!
Iron is oxidised by oxygen to form iron (III) oxide
What is the SECOND stage of rusting!?
. Iron (III) oxide is hydrated by water.
How do you prevent rusting !?
Either by :
. Using barriers
. Sacrificial protection
Or
. Galvanising
What is the barrier method used to prevent rusting !?
. Coating the iron in paint, oil, grease or plastic, prevents the iron from coming in contact with oxygen or
water
What is the disadvantage of the barrier method used to prevent rusting !?
. This only works as long as the coating is intact (As soon as it breaks rusting happens)
What is the sacrificial protection method used to prevent rusting !?
. Attach a block of more reactive metal (E.g. magnesium) to the iron. This works by displacing the iron from the rust as soon as the rust forms.
What is the disadvantage of the sacrificial protection method used to prevent rusting !?
. The block of magnesium has to be replaced often.
What is the galvanising method used to prevent rusting !?
. This method specifically involves coating the iron in zinc
What is the advantage of using the galvanising method used to prevent rusting !?
It works both ways:
. The coating prevents oxygen and water from coming in contact with the iron.
. (and even if a crack appears)
. Zinc is more reactive than iron, so acts as sacrificial protection as well.
What is an alloy !?
. Alloys are mixtures of a metal with one or more of the elements usually other metals or carbon
What are three common alloys !?
. Steel
. Brass
. Bronze
What does the alloy steel consist of !?
. Iron + carbon
What does the alloy brass consist of !?
. Copper + zinc
What does the alloy bronze consist of !?
. Copper + tin
What characteristics do alloys have that differ from pure metals !?
. Alloys are harder than pure metals because the different sized atoms or ions prevent the layers of metal ions sliding over each other. This means the alloy is less malleable.
What is the use of iron !?
. Making steel
Why do we use iron to create steel !?
. Steel is more useful than iron
What is the use of low carbon steel !?
Ships, cars, bridges
Why do we use low carbon steelto make ships etc!?
. As it is strong, but low carbon can be hammered into various shapes.
What is the use of high carbon steel !?
. Tools, knives
Why do we use high carbon steel to create tools!?
. High carbon steel is less malleable and stiffer than low carbon steel.
What is the use of stainless steel!?
. Cutlery, cooking utensils
Why do we use stainless steel to create cutlery !?
Cr forms an oxide layer that resists corrosion, so stays shiny and clean
What is the use of copper !?
. Wires, cooking pans, water pipes
Why do we use copper to create wires, pans and pipes!?
Excellent, conductor of electricity
Excellent, conductor of heat
Unreactive and malleable
What is the use of aluminium!?
. Aircraft bodies
. Power cables
Why do we use aluminium to make aircraft bodies!?
Low-density and high-strength
