文献翻译材料概述文档格式.docx
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文献翻译材料概述文档格式.docx
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further
subdivided
into:
①Metal②Ceramics
③Composite
④Polymers,
etc
Metals
Metal
Alloys
elements
that
generally
have
good
electrical
thermal
conductivity.
Many
metals
high
strength,
stiffness,
ductility.
Some
metals,
such
as
iron,
cobalt
nickel,
magnetic.
At
low
temperatures,
some
intermetallic
compounds
superconductors.
What
is
difference
between
an
alloy
a
pure
metal?
Pure
come
from
particular
area
periodic
table.
Examples
include
copper
wires
aluminum
cooking
foil
beverage
cans.
contain
more
than
one
metallic
element.
Their
properties
can
changed
changing
present
alloy.
metal
alloys
stainless
steel
chromium;
gold
jewelry
usually
contains
nickel.
Why
used?
densities
applications
require
mass-to-volume
ratio.
alloys,
based
on
aluminum,
aerospace
for
fuel
economy.
fracture
toughness,
means
they
withstand
impact
durable.
important
metals?
Density
defined
material’s
mass
its
volume.
Most
relatively
densities,
especially
compared
to
polymers.
with
atoms
atomic
numbers,
lead.
However,
magnesium
but
weight.
Fracture
toughness
described
ability
avoid
fracture,
when
flaw
introduced.
nicks
dents
without
weakening
very
much,
resistant.
A
football
player
counts
this
he
trusts
his
facemask
won’t
shatter.
Plastic
deformation
bend
deform
before
breaking.
As
engineers,
we
usuallydesign
so
don’t
under
normal
conditions.
You
want
your
car
lean
east
after
strong
west
wind.
sometimes
take
advantage
plastic
deformation.
The
crumple
zones
absorb
energy
undergoing
break.
bonding
affects
properties.
In
outer
valence
electrons
shared
among
all
atoms,
free
travel
everywhere.
Since
conductheat
electricity,
make
pans
wires.
It
impossible
see
through
since
these
any
photons
light
reach
metal.
No
pass
through.
consisting
Adding
affect
density,
deformation,
conductivity
environmental
degradation.
example,
adding
small
amount
iron
will
it
stronger.
Also,
chromium
slow
rusting
brittle.
Ceramics
Glasses
ceramic
broadly
nonmetallic
material.
By
definition,
would
glasses;
however,
many
scientists
add
stipulation
“ceramic”
must
crystalline.
glass
material
does
crystalline
structure.
Such
said
amorphous.
Properties
useful
ceramics
glasses
melting
temperature,
hardness,
wear
resistance,
corrosion
resistance.
insulators.
special
properties:
magnetic
materials;
piezoelectric
few
superconductors
at
temperatures.
major
drawback:
typically
formed
melt.
This
because
most
crack
extensively
(i.e.
form
powder)
upon
cooling
liquid
state.
Hence,
simple
efficient
techniques
production
casting
blowing,
involve
molten
state,
cannot
ceramics.
Instead,
“sintering”
“firing”
process
used.
sintering,
powders
processed
compacted
shapes
then
heated
temperatures
just
below
point.
react
internally
remove
porosity
fully
dense
articles
obtained.
An
optical
fiber
three
layers:
core
made
highly
refractive
index
travel,
middle
layer
lower
known
cladding
protects
scratches
surface
imperfections,
out
polymer
jacket
protect
damage.
order
higher
cladding,
doped
small,
controlled
impurity,
dopant,
causes
slower,
light.
Because
greater
traveling
remain
due
total
internal
reflection
long
strikes
core/cladding
interface
angle
critical
angle.
phenomenon,
well
purity
glass,
enables
distances
little
loss
intensity.
Composites
two
types
polymer/ceramic
metal/ceramic
composites.
overall
composites
superior
individual
components.
example:
modulus
component,
aren’t
brittle
Two
are:
fiber-reinforced
particle-reinforced
Fiber-reinforced
Reinforcing
fibers
ceramics,
glasses,
polymers
been
turned
graphite
carbon
fibers.
Fibers
increase
matrix
material.
covalent
bonds
along
fiber’s
length
give
direction
break
extend
broken
moved.
difficult
composites,
making
fiberreinforced
expensive.
Fiberreinforced
advanced,
therefore
expensive
sports
equipment,
time-trial
racing
bicycle
frame
consists
thermoset
matrix.
Body
race
cars
automobiles
(or
fiberglass)
axis,
perpendicular
axis.
Fiber
composite
manufacturers
rotate
layers
directional
variations
modulus.
Particle-reinforced
Particles
reinforcing
mineral
particles,
particles
amorphous
materials,
including
black.
matrix,
decrease
permeability
ductility
example
automobile
tire
has
black
polyisobutylene
elastomeric
polymer.
Polymers
repeating
structure,
backbone.
structure
results
large
chainlike
molecules.
lightweight,
resistant,
easy
inexpensive.
characteristics
size
molecular
weight),
softening
points,
crystallinity,
mechanical
strength
toughness.
improved
using
reinforced
structures.
Important
Characteristics
Size.
Single
molecules
weights
10,000
1,000,000g/molthat
2,000
units
depending
structure!
significantly
affected
weight,
better
weights.
Thermal
transitions.
point
(glass
transition
temperature)
meltingpoint
determine
suitable
applications.
These
upper
limit
industrially
near
boiling
water
(100℃,
212℉),
usefu
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