Biomedical Engineering Reference
In-Depth Information
attractive for structural applications but they may be used in applications
under low or moderate loads. Moreover, the low friction resistance of CNT-
glass matrix composites can be exploited for applications demanding anti-
friction materials such as in pump manufacturing and components for the
automotive industry. Like carbon fiber-glass/glass-ceramic composites,
components such as bearings, seals, brake and gear systems can be
manufactured using CNT-glass/glass-ceramic composites.
Finally, the process of developing a porous glass after burning
incorporated CNTs may also be used for certain applications where
controlled (nano)porosity is required, such as in filters, catalyst supports or
sorbents.
7.8
Conclusions and scope
A comprehensive analysis of published data in the field of CNT-glass/glass-
ceramic matrix composite reveals the novelty of this new class of
nanocomposites and the significant scope that they have for technological
applications. During the last ten years, considerable progress has been made
and consolidated glass matrix composites with uniformly dispersed CNTs at
relatively high loadings (15wt%) are now a reality. Optimization of
composite powder preparation techniques to disperse CNTs homogeneously
in glass/glass-ceramic matrices and their densification with different
consolidation techniques is a significant achievement that delivers a variety
of manufacturing routes to suit the varying dimensional requirements of
composite products.
Although the effect of randomly dispersed CNTs on the hardness and
stiffness of glass/glass-ceramic matrices is still not clearly understood,
moderate improvements in fracture strength and toughness and thermal
conductivity have been conclusively observed; the significant increase in
electrical conductivity is particularly promising. Incorporating highly
aligned CNTs of high aspect ratio in one or more well-specified directions
remains to be achieved. Although challenging, such a configuration of
CNTs in composites will increase their functional and structural properties
tremendously, especially thermal conductivity (Otieno et al., 2010).
The interfaces in nanocomposites occupy a large area; it might be possible
in future to develop in-situ interfaces formed by the chemical reaction
between CNTs and the surrounding glass phase resulting in better
composite properties. Uniformly dispersed CNTs may also be utilized as a
carbon source for in-situ development of carbides in glass/glass-ceramic
matrices.
The optimum quality and nature of CNTs remains an open question, and
the answer is likely to vary with application. CNTs produced by different
techniques offer varying characteristics
in their purity, crystallinity,
