Biomedical Engineering Reference
In-Depth Information
to the system. The role of excess Cu powder was not only as a diluent to
control the concentration of Al
2
O
3
but also as a thermal conductor to
remove heat from the system during milling.
12.8 Conclusions
.
Metallic-ceramic nanostructured composite powders can be produced in
situ simply and successfully at room temperature through a mecha-
nochemical route using high-energy ball milling. The subsequent
consolidation produces nanocomposites with the desired microstructure
and mechanical characteristics.
.
Despite a number of studies having been carried out in different
laboratories to synthesize nanocomposite powders, direct comparison
and prediction of the course of the process and/or product properties is
still very difficult (even when the precursors have a similar character).
Using different kinds of mills and procedures for milling influences the
input of mechanical energy to the treated material. Moreover, until now,
the mechanisms and kinetics of mechanochemical syntheses in solid-
solid systems are not fully understood. Therefore it seems to be
reasonable to carry out experimental studies to determine the progress
of reactions and quality of milling products at various milling stages in
relation to the milling conditions and to collect the data in order to
formulate a theory of mechanochemical processes.
.
In the case of composite mechanosyntheses with a metal matrix it is
especially important to inhibit self-propagating explosive reactions and
to transform to the progressive ones by wider use of soft mecha-
nochemistry (acidic, basic, hydrated salts) or, for example, different
PCA.
Based on the results of two practical examples of syntheses, the
transformation of combustion reactions to progressive reactions is shown
by applying copper and nickel hydroxocarbonates as composite precursors
(even if different in nature) instead of metal oxides, CuO and NiO.
12.9 Acknowledgements
The author would like to thank Professor Yu. G. Shirokov of the Ivanovo
State University of Chemistry and Technology, Russian Federation, who in
1995 inspired the study of mechanochemical processes.
The Polish Ministry of Science and Higher Education (Project Nos PB 4
T09B 07024 and PB 1 T09B 023 30) and the State Committee for Scientific
Research (Grants CUT/C-1/DS) provided financial support (2002-2008).
