ceramics, composites, polymers Flashcards

1
Q

whats a ceramic + type of bonding

A

combination of one or more metals with non-metallic element
- ionic or covalent bonding

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2
Q

mechanical prop. of ceramics 6/8

A

brittle
high hardness + compressive strength
low density
wear + chemical resistant
low thermal + electrical conductivity
high melting point

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3
Q

engineering ceramics

A

made to me more dense, hence stronger
- oxide ceramics
- non oxide ceramics

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4
Q

composite ceramics

A

carbon fibre reinforced silicon carbide used for braking systems in high performance cars

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5
Q

glass

A

soda lime, borosilicate, lead glasses
- basic ingredient is silica
- transparent to light
- brittle, shatters to impact loads
- weak tension
- strong compression

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6
Q

traditional clay ceramics

A

porcelains, earthenware, stoneware
p: fine tablewear, science equip
e: bricks
s: tiles

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7
Q

what is a composite + adv 3

A

combination of 2/+ different materials at a macroscopic level
- materials do not dissolve or blend into each other
- high strength + stiffness
- low weight ratio
- can be designed in addition to structure

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8
Q

fibre reinforcement

A

consist of matrix and fibres
- contribute to prop..
strength + stiffness, heat conductivity, chemical or electricity resistance

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9
Q

composite for brake lining

A

asbestos:
- resistant to high temp, good frictional prop
- asbestos fibres mixed with bronze particles bonded together with resin

sintered metal composites:
- metal particles pressed and bonded together with resin
- good heat dissipation
stable coeff of friction

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10
Q

what polymer + characteristics 3

A

material composed of long molecular chains formed by linking shorter chain molecules
- high strength and rigidity with low creep
- maintain over range of temps

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11
Q

addition polymerisation

A

process linking same monomers into larger polymer molecules
- NOT changing chemical composition NO by product
- most polymers made this way eg perspex

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12
Q

condensation polymerisation

A

two or more different monomers react together to produce a polymer WITH by product
- wide range of plastics eg nylon

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13
Q

thermosoftening/thermoplastic

A
  • long molecules entangled together
  • links between chains are strong primary covalent bonds, bonds btw links r weaker secondary bonds
  • low temp: solid, molecules tgt
  • heated, molecules move apart, seperate bonds, weaker chains, molecules move freely, reshape polymer
  • cooling, bond reestablish and solidify new shape
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14
Q

thermosetting

A

similar to thermoplastic but with chemically active sites along chains
- sets off sites forming covalent bonds along n btwn chains forming 3d net like structure
- molecule not free, harden material
- non crystalline and stronger than thermoplastics

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15
Q

5 prop of polymers

A

low thermal conductivity
lower density
corrosion resistant
more ductiles
lower hardness + stiffness
higher creep value

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