plastics, elastomers and ceramics Flashcards
what are polymers?
lightweight, corrosions resistant, electrical insulators with relatively low tensile strengths and melting points
why are they so popular?
ease with which they can be used to manufacture products and relatively low density
polymers are based on?
long chains of molecules
long chains are constructed from?
smaller molecules called monomers
the stress strain behaviour of polymers is?
generally non linear and time dependant
polymers exhibit both elastic and non elastic behaviour
elastomers are rubber
do ceramics creep?
no
everyday examples of ceramics?
brick and glass
3 categories of composites?
particulate, fibre and laminar
name of test used to test a structures resistance to impact loading?
charpy test
what is the energy absorbed by the structure called?
impact energy
why are alloys used in orthopaedic implants resistant to corrosion?
derived from an inert film covering the surface of the metal, usually an oxide, called the passivation layer
stainless steels contain 12-18%?
chromium
what gives stainless steel its corrosion resistant property?
chromium
name of the alloy used in orthopaedics?
316L (l for extra low carbon)
titanium based alloys have a higher strength to weight ration than aluminium
a fatigue fracture has relatively smooth region marked by concentric markings that may allow the origin of the fracture to be found. The rest of the fracture is granular or fibrous in appearance.
fatgue fracture = stress fracture = march fracture
y
plastics can be divided into ?
thermoplastics and thermosets
what do thermoplastics display?
plastic behaviour at high temperatures
which ones can be reformed?
thermoplastics
can not be reformed as during their formation at high temperatures, a by product is released from the material. harden at certain temperatures. this respects their recyclability
y
everyday examples of ceramics?
brick and glass
