Appeal No. 97-1417
Application No. 08/273,040
pyrolysis is inherent in the Liimatta et al
impregnate.
However, appellants argue that the polysilazanes in
Liimatta are not the same as those claimed. More specifically
(Brief, pp.5-6):
Claim 1 requires a skin comprising a first cloth
of ceramic material impregnated with an inorganic
resin which, under pyrolysis, provides an elemental
carbon-free material and, with increased
temperature, gradually converts from the liquid
state to a resilient state and then to a solid state
by about 1200EF. Even further, nowhere in Liimatta
et al. is there a teaching or even a suggestion that
the materials taught therein are limited to those
"which, under pyrolysis, provides an elemental
carbon-free material and, with increased
temperature, gradually converts from the liquid
state to a resilient state and then to a solid state
by about 1200EF". [Emphasis added.]
Manifestly, the resins disclosed in Liimatta are organic.
According to Liimatta, the disclosed invention is directed to
(Abstract):
A crosslinkable preceramic composition suitable for
use as an infiltrant for porous ceramics, such as
fiber-reinforced ceramic composites, comprises about
75-99% by weight of a low molecular weight
polysilazane and about 1-25% by weight of an
unsaturated organic or organosilicon compound
containing at least two alkenyl groups, preferably
methylvinylcyclosilazane.
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