Geoscience Reference
In-Depth Information
Table 10.4 (Continued)
Process
Advantages
Disadvantages
Composites
Particle Size
Rapid expansion of supercritical fluids
Wide range of compositions
including amorphous
powders and
nonequilibrium materials;
fast reaction times
(10
2
5
s); lower
temperatures than plasma
process
Requires high pressure
and high
temperature;
corrosive solvents;
some
agglomeration;
machined nozzles to
improve
morphology
Oxides; (SiO
2
, GeO
2
,
SiO
2
GeO
2
) fiber
precursors
(polycarbosilane);
labile, explosive
materials
0.01
1.3
μ
m
(ceramics)
,
0.1
μ
m
fiber, 1
μ
m
particle
(polymers)
Reductive dehalogenation of elemental halides
Low temperature, any
combination of elemental
halides that can be
reduced by alkali metals
Crystallization
requires higher
temperatures; high-
speed, high-shear
stirring needed;
starting materials
can be expensive;
reactions are
explosive or
combustible
Amorphous precursors
of TiB
2
, SiC, B
4
C,
and other borides
and carbides, SiC/
TiC, SiC/TiN
Source: From the works of M. Yoshimura and S. Somiya.
