1: Introduction Flashcards
Define material
substances of which an object is composed or can be made. can be almost any solid that can be put in shape.
which aren’t materials ? why ?
iron, helium, silica, h20, ethanol, wood, leather, concrete, polystyrene, epoxy, teflon, latex, diamond, boron nitride, fibreglass, co2, sodium chloride
helium
ethanol
air
co2
note - gases aren’t rly materials
what is the subatomic structure ? does it play a role in a materials structure ?
arrangement of its internal components,
subatomic: electrons in atoms, interaction with nucleus
yes - the field of protons and electrons defines interactions w other elements.
atomic structure refers to what ? what dimension range?
organization of atoms in molecules or crystals
0.1nm
nanostructure refers to what ? what dimension range?
aggregates and particles of less than 100nm
100nm
microscopic structure refers to what ? what dimension range?
related to large groups of atoms: phases
microscopic observation possible
100nm to several nm
macroscopic structure refers to what ? what dimension range?
naked eye observable aspects
a few mm
properties depend on what ?
properties depend on structure
ex: hardness vs structure of steel
-> harder as cooling rate increases
processing can do what
change the structure
ex: structure vs cooling rate
for example, how can the resistivity of copper be changed? how will it be affected ?
adding impurities increase resistivity
deforming increases resistivity
describe transmittance; why does this occur ?
aluminum oxide may be transparent, translucent, or opaque depending on material structure
transparent: single crystal
translucent: polycrystalline, low porosity
opaque: polycrystalline, high porosity
name 4 classes of materials
metal
polymer
ceramic
composite
describe metallic bonding
in metals, electrons are free to move, they’re not bound to any atom - same applies to when they’re in bonds
this is why they’re good thermal/electrical conductors.
also not transparent to visible light.
ceramics (and glasses) are a compound of what
compound between metallic and non-metallic element (often oxides, nitrides, carbides, ie metal w oxygen)
are ceramics chemically reactive
not rly, if u put a strong acid in glass, nothing happens
define ceramics. define glasses.
ceramics are crystalline, inorganic, non-metals
glasses are non-crystalline solids
describe polymers (including molecular structure/composition)
very large molecular structure (often organic compounds, chemically based on carbon, hydrogen, and non-metallic elements)
low densities, cheap to put in shapes, can be flexible, properties often imaged by a pack of fibres
describe composites composition
generally a combination of 2 or more different materials
can be at micro or macro scale
which are composites
iron, helium, silica, h20, ethanol, wood, paper, leather, polystyrene, bread, stainless steel, epoxy, latex, glass, diamond, air, fibreglass, concrete, sodium chloride
wood, paper, leather, bread, latex, fibreglass, concrete
note there are some property charts for each class at the end of slides.
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