Geoscience Reference
In-Depth Information
Figure 3.10 Cross section of a typical Morey-
autoclave
[28]
.
Plunger
Cover
Seal disk
Shoulder
Liner
1
in. diameter
Casing
suitable furnace so that the entire Morey-autoclave and closure lie within the ele-
ment of the furnace. At the end of the run, the vessel is quenched in a jet of air fol-
lowed by dipping in water and the closure seal is broken.
Cone Closure
By 1948, Tuttle at the Geophysical Laboratory had designed an ingenious cone-in-cone
seal for a small vessel with no threads to seize. Although this “Tuttle apparatus” could
go to much higher temperatures, and the pressure could be independently controlled by
a drilled lower seat, it had very small volumes, and it did not catch on.
These autoclaves are known as cold-cone-seal autoclaves, and also as Tuttle
autoclaves (
Figure 3.11
)
[34]
.ATuttle bomb consists of a stainless steel, low-
carbon steel, or more exotic alloy such as Inconel, Udimet, or Stellite (Co alloy),
test tube closed by a cone-in-cone seal. As with the Morey vessels, here also the
entire vessel assembly is kept inside the furnace. The seal is closed by weights
acting through heat-resistant alloys above and below the vessels. The cone at the
lower end of the support rod is machined to 59
, the cone or the vessel to 60
; this
results in a ring seal. At pressures exceeding 2 kbar and temperatures above 800
C,
these cones have to be machined after each experiment. Pressure is transmitted to
the sample through an axial hole in the lower support rod, and temperature is mea-
sured by placing a thermocouple in a well of the vessel within 3 mm of the sample.
A vertical split furnace is mounted on a hinge allowing it to be swung clear of the
vessel during loading or quenching. This vessel can be used up to 800
C at 4 kbar.
In 1949, Tuttle described a modification to his earlier design, which is much eas-
ier to use. This consists of a longer vessel in which the open end and seal are outside
the furnace; hence the term “cold-cone seal” (although in the real sense it is far from
being cold). Pressure is transmitted to the sample, which is contained in a sealed
capsule, through a hole in the closure. The capsules are normally made up of noble
metals. These vessels may be operated closure up, closure down, or horizontally.
The ratio of the vessel diameter to the hole diameter (wall diameter) determines the
