H.O. Pierson. Handbook of carbon, graphite, diamond and fullerenes. Properties, processing and applications. 1993
.pdf186 |
Carbon, |
Graphite, |
Diamond, |
and |
Fullerenes |
|
|
||||||
3.4 |
Structure |
of Mesophase-Pitch |
Carbon |
Fibers |
|
|
|||||||
|
Cross |
Section. |
The |
cross-section |
structure of |
mesophase-pitch |
|||||||
carbon |
fibers |
|
is one |
of the four |
types |
shown in Fig. 8.12 |
and is determined |
||||||
by |
the |
spinning method, |
the |
temperature |
of |
stabilization, and the |
partial |
||||||
pressure of |
oxygen. t2)t19) The |
formation |
of a skin-core |
structure |
or skin |
||||||||
effect |
is often |
observed. |
This |
|
structure is similar to that |
of the PAN-based |
|||||||
carbon |
fiber |
shown |
in Fig. 8.8 |
above. |
|
|
|
|
|
Radial |
Onion-Skin |
Onion-Skin |
Onion-Skin |
|
and Center- |
and Center |
|
|
Radial |
Random |
|
Figure 8.12. Cross-section of the various structures observed in pitch-based carbon fibers.r2]
|
Interlayer |
Spacing |
and |
Crystallite |
|
Size. |
|
The |
increase |
of |
the |
|||||||||||||||
apparent |
crystallite |
size |
of |
mesophase-pitch |
|
fibers |
as |
a function |
of heat- |
|||||||||||||||||
treatment |
is shown |
in Fig. 8.7, |
and |
the decrease |
of the |
interlayer |
spacing |
|||||||||||||||||||
(c spacing) |
in Fig.8.9.p) |
|
Th e spacing |
of the |
heat-treated |
|
fiber |
is relatively |
||||||||||||||||||
close to that of the ideal graphite |
crystal |
(- |
0.340 |
nm |
vs. |
0.3355 |
nm), |
|||||||||||||||||||
indicating |
a decreased |
turbostratic |
stacking |
of the |
basal |
planes |
and |
a well- |
||||||||||||||||||
ordered |
structure. |
in this |
respect, |
the |
difference |
between |
these |
fibers and |
||||||||||||||||||
the |
PAN-based |
fibers is pronounced. |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|||||||||
|
The |
large |
crystaiiites |
of the |
heat-treated |
pitch-based |
fibers, |
which |
is |
|||||||||||||||||
structurally |
|
close to the |
perfect |
graphite |
crystal |
and |
well |
aligned |
along |
the |
||||||||||||||||
fiber |
axis, |
offer |
few |
scattering |
sites |
for |
phonons. |
This |
means |
that |
these |
|||||||||||||||
fibers |
have |
a high |
thermal |
conductivity |
|
along |
the |
fiber |
axis |
since, |
as |
|||||||||||||||
mentioned |
|
in Ch. 3, Sec. 4.3, the transfer |
of heat |
in a graphite |
crystal occurs |
|||||||||||||||||||||
mostly |
by |
lattice |
vibration |
(see |
Sec. |
6.6 |
below). |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Carbon |
Fibers |
187 |
|
However, |
this |
high |
degree of crystallinity |
also |
results |
in low shear |
and |
|||
compressive |
strengths. |
In addition, |
these carbon fibers tend to have flaws |
|||||||
such as pits, scratches, |
striations, |
and flutes. |
These flaws |
are detrimental |
||||||
to tensile |
properties |
but do not essentially |
affect |
the |
modulus and |
the |
||||
thermal |
conductivity.t16) |
|
|
|
|
|
|
|
4.0CARBON FIBERS FROM RAYON
Rayon-based |
fibers were the first carbon |
fibers |
produced |
commer- |
||||
cially. They were |
developed |
in the |
1960’s |
specifically |
for the reinforcement |
|||
of ablative |
componentsfor rockets |
and missiles. |
However, they are difficult |
|||||
to process |
into high-strength, |
high-modulus |
fibers and have been |
replaced |
||||
in most structural |
applications |
by |
PAN or pitch-based |
fibers. |
|
4.1Rayon Precursor
A |
number of rayon fibers are available, but |
the most |
suitable is the |
||
highly |
polymerized viscose |
rayon. |
The molecular |
structure |
is asfollows:tll) |
|
|
OH |
OH |
|
|
|
|
CH-0 |
CH-0 |
|
|
|
-CH’ |
\ |
|
\ |
|
|
I |
CH-0-CH’ |
CH-0 |
|
|
|
\ |
\ |
|
|
|
|
CH-CH |
CH-dH |
|
|
As can be seen, this structure |
has many heteroatoms |
(0 and H) which |
||||
must |
be |
removed. |
Moreover, many carbon atoms are |
lost |
due |
to the |
|
formation |
of volatile |
carbon oxides |
during pyrolysis. As a result |
the |
carbon |
||
yield |
is low (~30%) |
and shrinkage |
is high. |
|
|
|
4.2Processing
The rayon |
precursor |
is first heated to 400°C at the |
relatively slow |
rate |
of 10°C per hour. |
During |
this step, the fiber is stabilized; |
H,O is formed |
from |
188 |
Carbon, |
Graphite, |
Diamond, |
and |
Fullerenes |
|
|
|
|
|
|
|
|
||||||||||||||||||
the hydroxyl |
|
groups |
in the |
molecule |
and |
the |
fiber |
depolymerizes |
with |
the |
|||||||||||||||||||||
evolution |
of CO and |
CO, |
and the formation |
of volatile, |
tar-like |
compounds. |
|||||||||||||||||||||||||
This |
depolymerization |
|
makes |
it impossible |
|
to stretch the fiber |
at this stage. |
||||||||||||||||||||||||
|
The |
heating |
rate can be increased |
and the carbon |
yield |
maximized |
by |
||||||||||||||||||||||||
heating |
|
the |
fiber |
in |
a |
reactive |
|
atmosphere |
such |
as |
air |
or chlorine, |
or |
||||||||||||||||||
impregnating |
it with |
flame |
retardants |
|
and |
carbonization |
|
promoters.t11l |
|
||||||||||||||||||||||
|
Carbonization |
|
is |
the |
next |
|
step |
|
and |
is carried |
out |
in |
an |
inert |
|||||||||||||||||
atmosphere |
|
at a temperature |
|
range |
of |
1000 |
- 1500°C. |
At this |
stage, |
the |
|||||||||||||||||||||
fiber |
has |
a low |
modulus |
(35 GPa, |
5 Msi), |
a low tensile |
strength |
and |
a low |
||||||||||||||||||||||
density |
(1.3 |
g/cm3). |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|||||
|
The |
degree |
of preferred |
orientation |
can |
be considerably |
increased |
by |
|||||||||||||||||||||||
stretching |
the carbonized |
fiber |
at very |
high |
temperature |
|
(- |
2700 |
- 28OO”C), |
||||||||||||||||||||||
resulting |
|
in a high-strength |
|
and |
high-modulus fiber. |
However, |
this |
requires |
|||||||||||||||||||||||
complicated |
|
and |
expensive |
equipment, |
the |
process |
is costly, |
and the |
yield |
||||||||||||||||||||||
of unbroken |
|
fiber |
is low. |
For these |
reasons, |
|
stretched |
fibers |
are no longer |
||||||||||||||||||||||
produced |
since |
they |
cannot |
compete |
with |
|
lower-cost, PAN-based fibers. As |
||||||||||||||||||||||||
mentioned |
in Sec. 2.2 above, |
PAN |
is stretched |
prior to carbonization, |
which |
||||||||||||||||||||||||||
is a considerably |
cheaper |
and |
|
more |
reliable |
than |
stretching |
at very |
high |
||||||||||||||||||||||
temperature. |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|||
|
The |
low-modulus |
rayon-based |
|
fibers |
are the only ones now produced |
|||||||||||||||||||||||||
in the form |
of carbon |
cloth |
or felt |
(Thornel |
|
WCA, VCL, VCK, and VCX from |
|||||||||||||||||||||||||
Amoco |
Performance |
Products). |
Primary |
uses |
are |
in carbon-carbon |
com- |
||||||||||||||||||||||||
posites and high-temperature |
|
insulation. |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|||||||||||||||
5.0 |
CARBON |
FIBERS |
FROM VAPOR-PHASE |
(CVD) |
REACTION |
|
|
||||||||||||||||||||||||
|
The |
direct |
growth |
of |
carbon |
fibers |
|
from the vapor-phase |
has |
been |
|||||||||||||||||||||
investigated |
|
for |
a number |
|
of |
years |
and |
the |
potential |
|
for |
producing |
a |
||||||||||||||||||
economically |
viable |
material |
with |
properties |
matching |
those |
of |
existing |
|||||||||||||||||||||||
PAN |
or pitch-based |
fibers appears good.f20)-f231 |
|
|
|
|
|
|
|
|
|
||||||||||||||||||||
|
Vapor-phase |
fibers |
are |
produced |
by the catalytic |
decomposition |
|
of a |
|||||||||||||||||||||||
hydrocarbon |
|
such as |
methane |
|
or |
benzene. |
The |
seed |
catalysts |
are |
iron |
||||||||||||||||||||
particles |
|
or iron metallo-organics |
|
such |
as ferrocene, |
(C,H,),Fe. |
Growth |
||||||||||||||||||||||||
occurs |
in the |
temperature |
|
range |
of 1000 |
- 1150°C. |
|
|
|
|
|
|
|
|
|
||||||||||||||||
|
Thefibersstill |
have |
a large |
spread |
in theirtensile |
strength |
(3000 - 8000 |
||||||||||||||||||||||||
MPa). |
However, |
the higher values |
|
compare |
favorably |
|
with |
those |
of high- |
||||||||||||||||||||||
strength |
|
PAN-based |
fibers |
(see |
following |
section). |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Carbon |
Fibers |
189 |
|
|
Vapor-phase |
fibers |
are only |
produced |
in short |
lengths |
at the |
present |
|
time. |
Maximum |
reported |
length |
is 50 mm with diameters |
from 0.5 |
- 2 pm. |
|||
Such |
short-length |
fibers |
would be suitable |
for the random |
reinforcement of |
||||
composites and |
in the production |
of carbon-carbon |
(see |
Ch. 9). |
|
6.0 PROPERTIES OF CARBON FIBERS
6.1The Filament Bundle
Carbon fibers |
are produced |
as a multifilament |
bundle known |
as a tow. |
||||||||
The number of filaments |
pertow |
is500, |
1,000, |
3,000, |
6,OOOor 12,000. The |
|||||||
smaller |
tow |
sizes |
are usually |
reserved |
for weaving |
and braiding |
while |
the |
||||
larger ones |
are for unidirectional |
tape winding. |
Both |
are used primarily |
in |
|||||||
aerospace |
applications. |
Still |
largertows, |
with filament |
count up to 320,000, |
|||||||
are also |
produced |
but |
mainly |
for less-demanding |
|
applications |
such |
as |
||||
sporting |
goods (see Ch. |
9).t8) |
|
|
|
|
|
|
|
6.2Fiber Testing
|
Carbon |
fibers |
are difficult to test due to theiranisotropic |
structure, |
their |
|||||||||||||
brittleness, |
the variation |
in their |
diameter, |
and the |
need |
to mold them |
in an |
|||||||||||
epoxy |
matrix to be |
|
able |
to measure |
some properties. |
Furthermore, |
the |
|||||||||||
strength |
|
is dependent |
to some degree |
on the length |
and diameter |
of the test |
||||||||||||
specimen |
and on the testing techniques. |
As a rule, the longerthe |
specimen |
|||||||||||||||
and |
the |
larger |
the |
fiber |
diameter, |
the |
lower |
the results, |
as |
shown in Fig. |
||||||||
8.13.t’) |
This |
is due |
to the |
greater |
|
chance |
of having |
structural |
defects |
in the |
||||||||
larger specimens. |
|
|
|
|
|
|
|
|
|
|
|
|
|
|||||
|
These |
factors |
must |
always |
be considered |
when comparing |
properties |
|||||||||||
from |
various |
groups |
of fibers and |
the |
data shown |
in the |
following |
sections |
||||||||||
is to |
be viewed |
with |
this |
in mind.t24) |
|
|
|
|
|
|
|
|
6.3Physical Properties of PAN-Based Carbon Fibers
PAN-based carbon |
fibers are heat-treated |
to various |
degrees |
of |
|||||
structural |
re-ordering. |
This determines the |
final |
strength |
and |
modulus |
of |
||
elasticity. |
The |
fibers |
are commonly divided |
into the three |
following classes |
||||
based on the |
value of the |
modulus: |
|
|
|
|
|
190 Carbon, Graphite, Diamond, and Fullerenes
n |
Standard-modulus |
fibers |
|
|
|
||
m Intermediate-modulus |
|
fibers |
(also |
known |
as Type II) |
||
= High-modulus |
fibers |
(also known |
as Type |
I) |
|||
Their |
properties are |
summarized |
in Table 8.6. |
|
|
|
I |
I |
I |
I |
I |
I |
2 |
8000 |
|
|
|
AS-4 |
(Hercules) |
|
B |
|
|
|
|
|||
|
|
|
|
|
|
|
|
5” |
6000 |
|
|
|
|
|
|
F |
|
|
|
|
|
|
|
5 |
4000 |
|
|
|
|
|
|
Q) |
|
|
|
|
|
|
|
= |
|
|
|
|
|
|
|
2 |
2000 |
|
|
|
|
|
|
C |
|
|
|
|
|
|
|
|
0 |
2 |
4 |
6 |
8 |
10 |
12 |
|
|
|
Fiber |
Diameter,pm |
|
|
6000 |
1 |
|
I |
I |
I |
I 1 |
g |
5000 |
- |
T 800 |
(Torayca) |
\- |
|
|
g |
4000 |
- |
- |
‘4 |
|
|
|
|
|
|
|
|
|
|
|
F |
3000 |
- |
T 300 (Torayca) |
|
|
|
|
2 |
|
|
|
|
|
||
f |
2000 |
- |
|
|
|
|
|
2 |
1000 |
- |
|
|
|
|
|
fi |
|
|
|
|
|
||
|
01 |
|
|
I |
I |
I |
1 |
|
|
0 |
|
5 |
10 |
20 |
30 |
|
|
|
Gauge |
Length, |
nm |
|
Figure 8.13. Effect of fiber diameter and gauge (specimen) length on the tensile strength of PAN-based carbon fibersr]
Carbon Fibers 191
Table 8.6. Summary of Strength Properties of PAN-Based Carbon Fibers
|
|
Standard |
(Type11) |
(Type1) |
|||
|
|
Intermediate |
High |
||||
|
|
Modulus |
Modulus |
Modulus |
|||
Modulus, |
GPA |
205 |
- 235 |
275- |
310 |
345 |
- 550 |
|
Msi |
30 |
- 34 |
40 - 45 |
50 - 80 |
||
Tensile |
strength, MPa |
3450 |
- 4650 |
4350 |
- 6900 |
1860 |
- 4140 |
|
ksi |
500 |
- 675 |
630 - 1000 |
270 |
- 600 |
|
Tensile |
strain, % |
1.4- |
1.6 |
1.6 |
- 2.2 |
0.81 |
- 0.9 |
Density, |
g/cm3 |
1.76 |
- 1.79 |
1.76 |
- 1.79 |
1.87 |
Properties |
of |
selected commercially |
available |
fibers are |
shown in |
||||||||||||
Table |
8.7. |
The |
data |
are obtained |
from |
suppliers’ |
technical |
brochures. |
|
||||||||
As a rule, higher-modulus fibers |
have lowertensilestrength |
and tensile |
|||||||||||||||
strain |
(elongation). |
|
The |
compressive-failure |
strain |
is |
dependent |
on |
the |
||||||||
modulus; |
it increases |
with |
decreasing |
modulus.t25] |
The |
failure |
occurs |
by |
|||||||||
kinking |
or microbuckling. |
This |
tendency |
is shown |
in both |
PAN- |
and |
pitch- |
|||||||||
based |
fibers. The mean-failure |
strain for PAN-based |
fibers |
is 2.11 - 2.66%. |
|||||||||||||
It is much |
lower |
for |
pitch-based |
fibers: 0.24 |
- 0.98%; |
this may be the result |
|||||||||||
of the |
greater |
suceptibility |
of |
these fibers |
to defects and |
handling. |
|
The |
|||||||||
testing |
procedure |
is described |
in |
Ref. 25. |
|
|
|
|
|
|
|
|
6.4Physical Properties of Pitch-Based Carbon Fibers
|
Carbon |
fibers based on isotropic pitch have low strength |
and |
modulus |
|||||||||||
with |
tensile |
strength |
averaging |
870 - 970 MPa and modulus |
of 40 - 55 GPa |
||||||||||
(Data from Carboflex, |
Ashland |
Oil Co., Ashland, KY, and Kureha |
Chemicals, |
||||||||||||
Japan). |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Mesophase |
pitch-based |
carbon |
fibers |
generally have |
the |
highest |
||||||||
stiffness |
of all carbon |
fibers |
with |
modulus |
of elasticity |
up to |
965 GPa (140 |
||||||||
Msi), |
considerably |
higher |
than |
PAN-based |
fibers. |
The tensile |
strength |
||||||||
however |
is much |
lower, averaging only |
half. |
As mentioned |
in the |
previous |
|||||||||
section, |
the |
compressive-failure |
|
strain |
is |
low. |
|
|
|
|
192 Carbon, Graphite, Diamond, and Fullerenes
Table 8.7. Strength and Modulus of Commercial Carbon Fibers (Partial Listing)
|
|
|
|
|
|
|
Tensile |
|
|
|
|
|
|
|
|
|
|
strength |
Modulus |
||
Product |
|
|
|
|
Mpa |
ksi |
GPa |
Msi |
||
Standard |
Modulus |
|
|
|
|
|
|
|
||
AS-4 |
(1) |
|
|
|
|
3930 |
570 |
248 |
36 |
|
Celion G30-500 (2) |
|
|
|
|
|
|||||
Thornel T-300 (3) |
|
3650 |
530 |
230 |
33 |
|||||
Torayca T-300 (4) |
|
3525 |
512 |
230 |
33 |
|||||
Grafil 33-650 (5) |
|
|
4480 |
650 |
|
|
||||
Intermediate |
Modulus |
(Tvpe |
II) |
|
|
|
|
|||
IM-6 |
(1) |
|
|
|
|
4340 |
630 |
275 |
40 |
|
IM-7 |
(1) |
|
|
|
|
5030 |
730 |
275 |
40 |
|
IM-8 |
(1) |
|
|
|
|
5860 |
850 |
275 |
40 |
|
IM-9 |
(1) |
|
|
|
|
6890 |
1000 |
275 |
40 |
|
Celion |
G40 |
- 600 |
(2) |
|
4140 |
600 |
|
|
||
Celion |
G40 |
- 700 |
(2) |
|
4820 |
700 |
|
|
||
Celion |
G40 |
- 800 |
(2) |
|
5510 |
800 |
|
|
||
Thornel T-650/42 (3) |
|
4820 |
700 |
298 |
42 |
|||||
Hitex 46-8 (6) |
|
|
|
5760 |
825 |
296 |
43 |
|||
Hiah Modulus (Tvpe |
I) |
|
|
|
|
|
||||
UHM |
(1) |
|
|
|
|
4140 |
600 |
448 |
65 |
|
Celion GY-70 (2) |
|
|
1860 |
270 |
520 |
75 |
||||
Torayca |
M60 |
(4) |
|
|
2410 |
350 |
550 |
80 |
||
(1) Product |
of Hercules, Magma, |
UT |
|
|
|
|||||
(2) Product |
of BASF, |
Germany, and Charlotte, NC |
|
|
||||||
(3) Product |
of Amoco |
Performance |
Products, |
Atlanta, |
GA |
|
||||
(4) Product |
of Toray, |
Japan |
|
|
|
|
|
|||
(5) Product |
of Grafil, |
Sacramento, |
CA |
|
|
|
||||
(6) Product |
of BP Chemicals, |
UK, |
and Santa |
Ana, CA |
|
|
Table 8.8 lists the range of property values of some commercially available fibers (P-series from Amoco Performance Products, Atlanta, GA).
The strength and modulus of pitch-based carbon fibers increase with increasing heat-treatment temperatures as shown in Fig. 8.14 .[“I
|
|
|
|
Carbon Fibers 193 |
Table 8.8. Summary |
of Physical Properties of Mesophase Pitch-Based |
|||
Carbon Fibers |
|
|
|
|
Tensile |
modulus, |
GPa |
380 - 827 |
|
|
|
Msi |
55- |
120 |
Tensile |
strength, |
MPa |
1900 |
- 2370 |
|
|
ksi |
274 |
- 350 |
Tensile |
strain, % |
|
0.25 |
- 0.5 |
Density, |
g/cm3 |
|
2.0 |
- 2.18 |
|
800 |
1200 |
1600 |
2OW |
2400 |
2800 |
3200 |
|
|
|
|
Heat-Treatment Temperature, “C |
|
||||
|
800 |
|
I |
I |
I |
I |
1 |
|
m |
|
|
|
|
|
|
|
|
8 . |
600 |
- |
|
|
|
|
|
|
s |
|
|
|
|
|
|
|
|
: |
400 |
- |
|
|
|
|
|
|
S |
|
|
|
|
|
|
|
|
ifiii |
200 |
- |
|
|
|
|
|
|
s |
|
|
I |
I |
I |
I |
I |
|
|
O- |
|
|
|||||
|
|
|
|
|
|
|
|
|
|
800 |
1200 |
1600 |
2060 |
2400 |
2800 |
3200 |
Heat-Treatment Temperature, “C
Figure 8.14. Tensile strength and modulus of pitch-based carbon fibers as a function of temperature.[“l
194 |
Carbon, |
Graphite, |
Diamond, |
and Fullerenes |
|
|
|
||||||
6.5 |
Properties |
of Rayon-Based |
Carbon |
Fibers |
|
|
|
||||||
The properties |
of stretched-graphitized |
rayon-based |
carbon fibers are |
||||||||||
shown |
in Table |
8.9. |
The |
data |
is to |
be considered |
for |
its |
historical |
value, |
|||
since |
the material |
is no longer |
produced |
commercially |
(data from |
Union |
|||||||
Carbide |
Corp.) |
|
|
|
|
|
|
|
|
|
|
|
|
Table |
8.9. Summary |
of Physical |
Properties |
of Rayon-Based |
Carbon |
Fibers |
|||||||
|
|
Tensile |
modulus, |
GPa |
173-520 |
|
|
|
|||||
|
|
|
|
|
|
|
Msi |
25 |
- 75 |
|
|
|
|
|
|
Tensile |
strength, |
MPa |
1200 |
- 2650 |
|
|
|||||
|
|
|
|
|
|
|
ksi |
180- |
385 |
|
|
|
|
|
|
Density, g/cm3 |
|
|
1.40 |
- 1.80 |
|
|
|
6.6Thermal and Electrical Properties of Carbon Fibers
Thermal |
Conductivity. |
|
As |
mentioned |
above, the |
fibers |
with |
the |
|||||||||||||||
highest |
degree |
|
of |
orientation |
such as |
the |
|
pitch-based |
|
fibers |
have |
the |
|||||||||||
highest |
thermal |
|
conductivity. |
As |
shown |
in |
Table |
8.10, |
their |
conductivity |
|||||||||||||
along |
the |
axis |
is higher |
than |
even |
the |
best |
metal |
conductor. |
PAN-based |
|||||||||||||
fibers, |
|
on |
the other |
hand, |
have |
much |
lower |
|
conductivity |
because |
of their |
||||||||||||
more |
pronounced |
|
isotropic |
structure. |
|
|
|
|
|
|
|
|
|
|
|
|
|||||||
Thermal |
Expansion. |
|
The |
thermal |
expansion |
of |
carbon |
fibers, |
|||||||||||||||
measured |
along |
the axis, |
is extremely |
low |
and |
similar |
to |
that |
|
of |
pyrolytic |
||||||||||||
graphite in the |
abdirection, |
i.e., |
slightly |
negative |
at room temperature |
and |
|||||||||||||||||
slowly |
|
increasing |
with |
increasing |
temperature |
(see Ch. 7, Fig. |
7.11). |
The |
|||||||||||||||
thermal |
coefficient |
of expansion |
(CTE) |
|
at room |
temperature |
is as follows |
||||||||||||||||
(data |
from |
Amoco |
Performance |
Products). |
|
|
|
|
|
|
|
|
|
|
|||||||||
|
|
|
PAN-based |
fibers: |
-0.6 to -1 .l |
m/m.K |
x 1Oe6 |
|
|
|
|
|
|
||||||||||
|
|
|
Pitch-based |
fibers: |
-1.3 |
to -1.45 m/m-K |
x 1Oe6 |
|
|
|
|
|
Carbon Fibers 195
Table 8.10. Thermal Conductivity of Carbon Fibers and Selected Metals
|
|
|
|
|
|
|
|
|
|
|
Thermal |
Conductivity |
|
|
|
||||
|
|
|
Material |
|
|
|
|
|
|
at 25°C (W/mX) |
|
|
|
|
|||||
|
|
|
Silver |
|
|
|
|
|
|
|
|
|
420 |
|
|
|
|
||
|
|
|
Copper |
|
|
|
|
|
|
|
|
385 |
|
|
|
|
|||
|
|
|
Pyrolytic |
graphite |
|
|
|
|
|
|
|
|
|
|
|
||||
|
|
|
|
(ab |
directions) |
|
|
|
|
390 |
|
|
|
|
|||||
|
|
|
PAN-based |
fibers* |
|
|
|
|
|
|
|
|
|
|
|||||
|
|
|
|
(along |
the |
axis) |
|
|
|
8 - 70 |
|
|
|
|
|||||
|
|
|
Pitch-based |
fibers* |
|
|
|
|
|
|
|
|
|
|
|||||
|
|
|
|
(along |
the |
axis) |
|
530- |
1100 |
|
|
|
|
||||||
|
|
|
*Data |
from |
Amoco |
Performance |
|
Products |
|
|
|
|
|||||||
Electrical |
Resistivity. |
|
|
Like |
the |
thermal |
properties, |
the |
electrical |
||||||||||
resistivity |
of |
carbon |
fibers, |
measured |
along |
the |
axis, is |
similar |
to that |
of |
|||||||||
pyrolytic |
graphite |
in the |
ab |
direction |
and |
|
approximately |
an |
order |
of |
|||||||||
magnitude |
higher |
than |
metal |
conductors such |
as aluminum |
or copper, |
as |
||||||||||||
shown |
in Table |
8.11. |
|
|
|
|
|
|
|
|
|
|
|
|
|
||||
Table |
8.11. |
Electrical |
Resistivity |
of Carbon |
Fibers and |
Selected |
Metals |
||||||||||||
|
|
|
|
|
|
|
|
|
|
|
|
Electrical |
Resistivity |
|
|
|
|||
|
|
|
|
Material |
|
|
|
|
at 25°C @Q.m) |
|
|
|
|
||||||
|
|
|
|
Aluminum |
|
|
|
|
|
|
0.026 |
|
|
|
|
||||
|
|
|
|
Copper |
|
|
|
|
|
|
|
0.017 |
|
|
|
|
|||
|
|
|
|
Pyrolytic graphite |
|
|
|
|
|
|
|
|
|
||||||
|
|
|
|
|
|
ab directions |
|
|
|
2.5 |
- 5 |
|
|
|
|
||||
|
|
|
|
Pitch-based |
fibers* |
|
|
|
|
|
|
|
|
||||||
|
|
|
|
|
|
along |
the |
axis |
|
|
2.2 |
- 2.5 |
|
|
|
|
|||
|
|
|
|
PAN-based |
|
fibers* |
|
|
|
|
|
|
|
|
|||||
|
|
|
|
|
|
along |
the |
axis |
|
|
9.5 |
- 18 |
|
|
|
|
*Data from Amoco Performance Products