Characterization and control of the fiber-matrix interface in ceramic ...

9. EXPERIMENTAL PROCEDURES
9.1 Deposition System
The apparatus employed for the deposition and infiltration
experiments is shown in Figure 9.1.
The furnace consists of an aluminum
water jacket with two concentric tubular shells capped at the ends and
fitted with a water inlet at the bott:ono edge and an outlet at the top.
The interior of the jacket is insulated with a low-density graphite felt
and a thin layer of graphite foil, which reduces exposure of the interior
to direct heating and increases efficiency sf the furnace through lower
heat loss to the jacket. Ports have also been provided in the shell for
thermocouple access and gas-purge lines.
The jacket is bolted to an upper extension and to a lower base.
O-ring seals join the components. The upper extension is aluminum, but
no means of cooling is provided, This upper section contailis the exllaust
outlet and is capped with a removable lid. The lid, which is also
aluminum, is water-cooled with a 40-mrn sight port equipped with gas
purges to prevent condensation on the 6-mm-thick quartz window during
deposition. The lid is attached to the extension using a series of bolts
around the upper diameter and is sealed with an O-ring.
The base section is also uncooled. The base provides support for
the furnace, feed-throughs for water-cooled electrodes, access for the
gas-distribution system, and support for the heating element. The
graphite heating element is mounted to electrodes, which are attached to
the base through a ceramic insulator. The base is fitted with a center
port and a base plate with internal and external O-ring seals. The gas
distributor-specimen support is fed through the base plate into the
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