Geoscience Reference
In-Depth Information
Figure 3.7 Commercially available Tuttle cone-seal autoclave system (a); Tuttle cone- seal
autoclave assembly (b).
3.5 Autoclaves and Autoclave Designs
This forms the most important aspect of hydrothermal research. The advances in
the hydrothermal research go in parallel with the autoclave design. The earliest
autoclaves were very simple in design and generally made up of glass; the avail-
ability of suitable metals and alloys was limited. Besides, the main objective was
to synthesize some compound that resembled some natural mineral. Thus, the pres-
sure
temperature range was rather low. It was only after the first successful appli-
cation of stainless steel as the autoclave material
[10]
that
the design and
fabrication of autoclaves for higher pressure
temperature limits was actually initi-
ated. Such efforts resulted in the attempts to grow diamond and corundam crystals
during the 1870s
[23
25]
. The actual impetus for the design of new autoclaves
came during the 1940s with the development/discovery of several new alloys.
The complexity in the designing of the autoclaves also began. Further, during the
1970s, the designing of autoclaves (using a suitable alloy) for specific purposes
like the study of kinetics, solubility, and direct or visual observation of the hydro-
thermal reactions began. With the entry of scientists from different branches of
science into hydrothermal research, the diversity and adaptability of hydrothermal
research began to make it a more interdisciplinary science than just the study of
mineral or phase equilibria and crystal growth. The materials processing under
hydrothermal conditions got a new impetus. All these developments resulted in the
designing of a large number of new autoclaves, which are together grouped under
novel designs. Byrappa
[26]
has reviewed various autoclave designs in detail. Here,
it is extremely difficult to discuss the development of each and every autoclave
