Carbon Nanotube Reinforced Composites: Metal and Ceramic ...
Carbon Nanotube Reinforced Composites: Metal and Ceramic ...
Carbon Nanotube Reinforced Composites: Metal and Ceramic ...
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commercialization of CNT-reinforced composites, the fabrication <strong>and</strong> consolidation<br />
methods must be both cost effective <strong>and</strong> competitive.<br />
Nanomaterials with unique physical properties, such as large surface area or aspect<br />
ratio have shown great potential for biological applications, including tissue engineering,<br />
biosensors, medical devices, <strong>and</strong> so on. The application of nanotechnology<br />
to biomedical engineering is a new frontier in orthopedics. Nanocomposites play a<br />
crucial role in orthopedic research since bone itself is a typical example of a<br />
nanocomposite [5, 6]. The fabrication of implant materials that mimic the structure<br />
<strong>and</strong> properties of human bones is a significant challenge for materials scientists.<br />
Bone is a composite material consisting of a calcium phosphate crystalline phase <strong>and</strong><br />
an organic collagen matrix. The calcium phosphate phase in bones differs in<br />
composition from stoichiometric hydroxyapatite [Ca 10(PO4)6(OH)2] by the presence<br />
of other ions such carbonate, magnesium <strong>and</strong> fluoride of which the carbonate<br />
content is about 4–8 wt% [7]. Sintered hydroxyapatite (HA) cannot be used as a st<strong>and</strong>alone<br />
load-bearing material for bones due to its brittle nature, so HA is mostly used as<br />
a coating material for bulk metallic implants. Therefore, CNTs with large aspect ratio,<br />
excellent flexibility, superior biocompatibility <strong>and</strong> bone cell adhesion appear to be<br />
suitable reinforcements for HA <strong>and</strong> other bioceramics. Apparently, orthopedic<br />
implant research is another area in which CNTs <strong>and</strong> their nanocomposites can be<br />
of significant importance [8]. Recently, Wang et al. reported that spark plasma<br />
sintered SiC/MWNTnanocomposites exhibit superior mechanical performance <strong>and</strong><br />
biocompatibility [9]. These nanocomposites can be used for bone tissue repair <strong>and</strong><br />
dental implantation on the basis of in vivo animal (rat) tests. Histological examination<br />
showed that there was little inflammatory response in the subcutaneous tissue, <strong>and</strong><br />
newly formed bone tissue was observed in the femur after implantation for four<br />
weeks [9].<br />
8.2<br />
Potential Applications of CNT–<strong>Ceramic</strong> Nanocomposites<br />
8.2 Potential Applications of CNT–<strong>Ceramic</strong> Nanocompositesj217<br />
In addition to thermal management applications in the electronic industries,<br />
ceramic–CNT nanocomposites with good thermal conductivity <strong>and</strong> fracture toughness<br />
are c<strong>and</strong>idates for leading edge applications such as thermal barrier coatings<br />
(TBCs) for gas turbine engines since they can improve the performance of turbine<br />
blades operate at extreme thermal <strong>and</strong> mechanical conditions [4]. <strong>Ceramic</strong>s with<br />
reduced thermal conductivity have been used as thermal barrier materials for TBCs<br />
of gas turbine engines. The CNT–ceramic nanocomposites for TBC applications can<br />
be fabricated by means of tape-casting or plasma-spraying techniques. Another<br />
possible area where ceramic–CNT nanocomposites can find useful application is<br />
light-weight armor made from boron carbide [10]. The inherently brittle nature of<br />
boron carbide can be overcome by incorporating CNTs, thus improving the ballistic<br />
performance considerably.<br />
It is anticipated that this novel emerging technology, nanotechnology, will have<br />
a substantial impact on biomedical engineering technology. At present, the