Biomedical Engineering Reference
In-Depth Information
effective method is needed to improve the wettability between ceramic
reinforcement and metals.
.
Cost. In order to get a uniform dispersion of nanoparticles, a large
amount of energy input is needed. The cost of manufacturing MMNCs
needs to be reduced for further application in industry.
.
Bulk material for structure material usage. Due to the high energy
density input needed, manufacturing bulk MMNC for
structure
material fabrication is limited.
6.2 Material selection
Compatibility between the reinforcement and the matrix is the most
important factor to build a successful MMC system. Matrices used are
metals including copper, magnesium and aluminum. All of these metals
have also been commonly used for microsize particulate reinforced MMC.
Most of the reinforcements used are low-dimensional materials, ceramic
particles and CNTs.
6.2.1 Reinforcement material
Ibrahim et al. (1991) summarized the selection criteria for ceramic
reinforcement, which include:
.
elastic modulus
.
tensile strength
.
density
.
melting temperature
.
thermal stability
.
coefficient of thermal expansion
.
size and shape
.
compatibility with matrix material
.
cost
.
availability in the market.
With the matrix material determined, the above factors should be evaluated
to choose a suitable ceramic reinforcement.
Of all the possible candidates, CNTs are the most popular reinforcement
used in MMNCs due to their rapidly developing fabrication technology.
CNT/ceramic and CNT/polymer nanocomposites have successfully
enhanced the mechanical properties of the matrix. CNT/metal systems
have made less improvement due to inferior mechanical properties, mostly
caused by the defects formed in bulk metals during the fabrication process.
However, the unique mechanical and physical properties of CNTs still make
them the most promising reinforcements for creating metal matrix structural
