Carbon Nanotube Reinforced Composites: Metal and Ceramic ...

56j 2 Carbon Nanotube–Metal Nanocomposites
Figure 2.9 CNTs dispersed on the surface of aluminum particles
of Al/2 wt% MWNT composite powder after milling for 0.5 h.
Reproduced with permission from [36]. Copyright Ó (2007)
Elsevier.
To observe the dispersion of MWNTs in Al matrix, the mill powders were fractured
mechanically. Figures 2.9 and 2.10 show SEM fractographs of the Al/2 wt% MWNT
sample after milling for 0.5 and 48 h, respectively. The MWNTs are found to
disperse uniformly on the flakes surface after milling for 0.5 h. Carbon nanotubes
also remain intact with the aluminum matrix after milling for 48 h. From a series
of SEM fractographs examination, MWCNTs are embedded in the aluminum matrix
once cold-welding particles of smooth surfaces begin to develop, that is, after milling
for 6 h.
More recently, Perez-Bustamante et al. employed MA technique to prepare
Al nanocomposites reinforced with 0.25, 0.5, 0.75 and 2 wt% MWNT [38]. Aluminum
powders were blended ultrasonically with MWNTs, mechanically milled in a high
energy shaker mill for 1–2 h, followed by sintering in vacuum at 550 C for 3 h.
The milling media (hardened steel) to powder ratio was fixed at 5 : 1. Figure 2.11 is
the TEM micrograph of as-sintered Al/2 wt% MWNT nanocomposite showing
good dispersion of CNTs in aluminum matrix.
Figure 2.10 Individual CNTs embedded in the aluminum particles
of Al/2 wt% MWNT composite powder after milling for 48 h.
Reproduced with permission from [36]. Copyright Ó (2007)
Elsevier.