C10: MATERIALS Flashcards

1
Q

What is an alloy?

A

a mixture of a metal with small amounts of other elements

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2
Q

Steels:
-main metal
-other elements
-uses

A

-main metal: iron
-other elements: carbon (stainless steel - chromium and nickel)
-uses: cutlery, construction, cars

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3
Q

Gold alloys:
-main metal
-other elements
-uses

A

-main metal: gold
-other elements: silver/copper/zinc
-uses: jewellery

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4
Q

How many carats pure gold?

A

24 carat

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5
Q

How do you calculate the % of gold in an alloy?

A

(no. of carats/24) x 100

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6
Q

Brass:
-main metal
-other elements
-uses

A

-main metal: copper
-other elements: zinc
-uses: brass instruments, brass pins in plugs

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7
Q

Bronze:
-main metal
-other elements
-uses

A

-main metal: copper
-other elements: tin
-uses: statues, coins

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8
Q

What is corrosion?

A

the destruction of materials (esp metals) by chemical reactions with water/O2

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9
Q

What is rusting?

A

corrosion when iron or steel reacts with oxygen and water

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10
Q

What is the word equation for rusting?

A

iron + oxygen –> iron oxide

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11
Q

What needs to be present for rusting to occur?

A

water

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12
Q

What are the 2 methods of preventing corrosion?

A

-protective layer
-sacrificial protection

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13
Q

Protective layer:
-how it works
-examples

A

-acts as a barrier which stops it reacting with O2 and water
-examples: paint, oil, plastic, any less reactive metal

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14
Q

Sacrificial protection:
-how it works
-examples

A

-zinc often used to coat iron nails because it is more reactive so any water and O2 that comes into contact with the nail reacts with the zinc and not with the iron
-examples: any more reactive metal

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15
Q

Clay

A

-soft when dug up out of the ground so it can be moulded into different shapes
-when fired at high temps it hardens to form a clay ceramic
-ideal for making pottery and bricks

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16
Q

Glass (properties)

A

-transparent
-can be moulded when hot
-brittle when thin

17
Q

What are the 2 types of glass

A

-soda-lime glass
-borosilicate glass

18
Q

How is soda-lime glass made?

A

-made by heating a mixture of limestone, sand and sodium carbonate
-when mixture cools it comes out as glass

19
Q

How is borosilicate glass made?

A

-made by heating a mixture of sand and boron trioxide
-when mixture cools it comes out as glass

20
Q

What are composites?

A

a material made from two or more different materials with contrasting properties

21
Q

What are the components of composite materials?

A

-the reinforcement (fibres/fragments of a material)
-the matrix (acts as a binder and holds reinforcement together)

22
Q

What are some examples of composites?

A

-fibreglass
-carbon fibre
-concrete
-wood

23
Q

Fibreglass:
-reinforcement
-matrix
-properties
-uses

A

-reinforcement: glass fibres
-matrix: polymer
-properties: low density, very strong
-uses: skis, boats, surfboards

24
Q

Carbon fibres:
-reinforcement
-matrix
-properties
-uses

A

-reinforcement: carbon fibres/nanotubes
-matrix: polymer
-properties: strong, light
-uses: aerospace, sports car manufacturing

25
Q

Concrete:
-reinforcement
-matrix
-properties
-uses

A

-reinforcement: aggregate (mixture of sand and gravel)
-matrix: cement
-properties: very strong
-uses: building (eg: pavements/in skate parks)

26
Q

Wood:
-reinforcement
-matrix

A

natural composite
-reinforcement: cellulose fibres
-matrix: organic polymer

27
Q

What are the 2 factors that influence the properties of a polymer?

A

-how it is made
-what it is made from

28
Q

What do the properties of poly(ethene) depend on?

A

-reaction conditions
-use of a catalyst

29
Q

How is low density (LD) poly(ethene) made?

A

-made from ethene
-moderate temp
-high pressure

30
Q

What are the properties and uses of LD poly(ethene)?

A

-low density
-flexible
-used for bags and bottles

31
Q

How is high density (HD) poly(ethene) made?

A

-made from ethene
-lower temp
-lower pressure
-catalyst present

32
Q

What are the properties and uses of HD poly(ethene)?

A

-high density
-more rigid
-used for water tanks and drainpipes

33
Q

The _________ that a polymer is made from determine the type of ______ that form between the polymer chains. these _____ _____ between the different molecule chains determine the _______ of the polymer

A

the monomers that a polymer is made from determine the type of bonds that form between the polymer chains. these weak bonds between the different molecule chains determine the properties of the polymer

34
Q

What are the 2 different types of polymers?

A

-thermosoftening polymers
-thermosetting polymers

35
Q

Thermosoftening polymers

A

-melt when heated
-weak intermolecular bonds between polymer chains
-can be remoulded

36
Q

Thermosetting polymers

A

-do not melt when heated
-strong covalent bonds form cross links between polymer chains
-when heated, cross links do not allow the chains to separate
-cannot be remoulded