Geoscience Reference
In-Depth Information
4
3
2
1
0
Figure 10.63 Man-made composites
[319]
.
Source: Courtesy of the National Academy Press, Washington, DC.
of rockets, reducing weight and providing strength and durability
[319]
. Composites
are highly useful in the fabrication of high-performance microelectronic devices con-
sisting of multilayer substrates—multiple layers of ceramic (alumina), metal, and
thin-film organic insulators. The fabrication of these substrates is made difficult by
a number of problems, prominent among which is that of ensuring adhesion
between the different components. These components commonly exhibit widely
divergent coefficients of thermal expansion and fundamentally incompatible sur-
face chemistries.
Tailoring the properties of the interface between the reinforcing component and
the matrix is a major application of chemistry in improving the performance of
composites. Failure in multilayer fiber-reinforced composite structures often occurs
either at
matrix interface. The
surface treatments, now used to modify the surface properties of reinforcing
fibers in composites, are largely empirical. In this regard, the hydrothermal method
of processing the materials to obtain composites and multilayers of ceramics
and coating of substrates on other materials is very significant. The literature data
available on composites are so vast that it is impossible to discuss each and every
material in this chapter. Therefore, we have chosen the most important material,
namely HAp-based composites, owing to their potential applications in modern
technology.
the fiber
matrix interface or at
the matrix
10.8.3 Hydrothermal Processing of HAp Coatings and HAp-Based
Composites
Industrial application of HAp requires its use in various forms, e.g., porous or
dense sintered body. Catalytic and chromatographic applications utilize powder
HAp. Recently, film HAp has become important as a coating for metal or ceramic
bodies, and tiny electronic devices such as sensors.
In order to overcome the inferiority of HAp in mechanical properties, the coat-
ing of HAp films has been attempted on bioinert materials of strength and/or tough-
ness, such as polycrystalline alumina (Al
2
O
3
), zirconia (ZrO
2
), titanium metal (Ti),
