Biomedical Engineering Reference
In-Depth Information
7.22
C
for 48 h. MWCNTs oxidized completely, leaving behind a porous silica
glass matrix.
(a, b) 10wt% MWCNT-SiO
2
composites thermally aged at 1000
8
7.7
Applications
Low density, improved fracture toughness, enhanced electrical and thermal
conductivity, resistance to oxidation at moderate to high temperatures, and
higher hardness and stiffness than polymers and some metals make CNT-
glass/glass-ceramic matrix composites an attractive choice for potential
applications where structural and thermal properties are required. In
aerospace, electronic and engine components, enhanced thermal conductiv-
ity is required for fast heat dissipation. CNT-glass/glass-ceramic compo-
sites, due to their higher thermal conductivities than the pure matrices, may
be used for space structural applications and as heat sink materials to
dissipate heat from electronic components. Applications requiring a sudden
temperature change may also be considered for CNT composites due to
their resistance to thermal shock and cycling, for example in the handling of
low-melting metals and glasses. CNT composites can also be used for
applications demanding intermediate temperatures up to 500
C and normal
air environments. Glass matrix composites containing CNTs can be
developed for the thermal protection of C/C composites and also as
thermal barrier coatings.
The tremendous increase in electrical conductivity of insulating glasses by
incorporating CNTs, dispersed or aligned, has added a new material family
for the electroceramics industry, in which electrical conductivity can be
tailored to the required application. The anisotropy in electrical and thermal
conductivity of CNTs can be used to fabricate glass matrix composites with
aligned CNTs, which can provide the desired thermal/electrical conductivity
in specified directions only. Due to their (modest) increased fracture
toughness, CNT-glass/glass-ceramic matrix composites are not
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(yet)
