ceramics, composites, polymers

Question 1

whats a ceramic + type of bonding

Answer 1

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

Question 2

mechanical prop. of ceramics 6/8

Answer 2

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

Question 3

engineering ceramics

Answer 3

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

Question 4

composite ceramics

Answer 4

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

Question 5

glass

Answer 5

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

Question 6

traditional clay ceramics

Answer 6

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

Question 7

what is a composite + adv 3

Answer 7

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

Question 8

fibre reinforcement

Answer 8

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

Question 9

composite for brake lining

Answer 9

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

Question 10

what polymer + characteristics 3

Answer 10

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

Question 11

addition polymerisation

Answer 11

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

Question 12

condensation polymerisation

Answer 12

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

Question 13

thermosoftening/thermoplastic

Answer 13

• 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

Question 14

thermosetting

Answer 14

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

Question 15

5 prop of polymers

Answer 15

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