Biomedical Engineering Reference
In-Depth Information
12.13
SEM microphotograph illustrating the product structure of a
combustion aluminothermic reaction during mechanical treatment
of a NiO-Al mixture (SEM Hitachi S-4700) (Wieczorek-Ciurowa and
Oleszak, 2008).
masses of the reagents was used to provide NiAl stoichiometry (Fig. 12.12a).
A small amount of Ni
3
Al was still present.
The composite powder Ni
3
Al/Al
2
O
3
is formed explosively in the NiO-Al
reagent system (Fig. 12.12b). The SEM microphotograph of the product is
shown in Fig. 12.13.
12.7 Other possible variants of the synthesis of metal
matrix-ceramic composites in Cu-Al-O and Ni-Al-
O elemental systems using mechanical treatment
ex situ
and
in situ
It has already been reported that copper and nickel as well as other
transition metals and intermetallics with these metals are important matrices
in composite materials with fine dispersion of Al
2
O
3
particles because of
their applications. For instance, cermetals such as Ni-Al/Al
2
O
3
are
candidates for military and civil aero engines as exhaust nozzle materials.
This type of composite is used in dentistry as a substance for fillings, in
prosthetics, as vacuum tube coatings for solar hot water systems, transistors,
capacitors, and so on (see, e.g. Grahle and Arzt, 1997; Ying and Zhang,
2000a,b; 2003; Morsi, 2001; Portnoy et al., 2002).
