Apparatus - Hydrothermal Technology - page 109

Figure 3.23 Schematic diagram of the autoclave
designed for solubility measurements [59] .
Weight
Spring
Teflon packing
Crystal
Pt mesh
Solution
Teflon liner
Rotation shaft
inclusions. Some of these experiments are not only hazardous but also have errors
in applications and equipment failure. Figure 3.25 shows a schematic diagram of
a rocking autoclave, which can be used for various types of studies [63] . These
autoclaves are made of stainless steel or other useful alloys and usually contain
self-energized closures. There can be two types of rocking autoclaves: (1) fixed-
volume systems and (2) flexible-cell systems. These systems are placed in
a furnace that rotates on an axis of 180 , approximately 10 times each minute.
The purpose of rocking the pressure vessel is for temperature stability and homo-
geneity as well as to mix the contents of the reaction cell, thereby accelerating
chemical exchange between solids and fluids and the attainment of equilibrium
[15] . These rocking autoclaves provide an extremely reliable and effective means
of conducting hydrothermal experiments under supercritical conditions [64] .A
reader can get more information on rocking autoclaves in Refs. [65] and [66] .
Multichamber Autoclave
Multichamber autoclaves are very useful in carrying out hydrothermal experiments
with separately placed charge nutrients and offer some advantages in the synthesis
of special materials. The reaction products occur through ion diffusion.
Yanagisawa et al. (1997) have designed and tested these multichamber autoclaves