Appeal No. 1996-1896
Application No. 08/206,973
Claim 1 is representative of the subject matter on appeal
and reads as follows:
1. A method of controlling the rate of deposition of
pyrocarbon onto a substrate while it is being levitated in an
enclosure along with a fluidized bed of particles in order to
produce a precise thickness of deposit of pyrocarbon of
uniform crystalline properties, which method comprises
establishing a bed of particles in fluidized condition in
a coating zone within an enclosure along with at least one
substrate to be coated, all of which are levitated by
supplying an upward flow of a gaseous atmosphere which
comprises an inert gas,
heating said bed of particles and said substrate to a
pyrolysis temperature in said coating zone and supplying said
levitating gaseous atmosphere in a form that includes a
mixture of a hydrocarbon component and an inert gas component,
each of which components is supplied to said coating zone at a
certain initial flow rate, such that pyrolysis of said
hydrocarbon occurs causing pyrocarbon to be deposited upon
surfaces of said substrate and upon said particles in said
coating zone,
monitoring either (a) the weight of said fluidized bed,
or (b) the differential pressure between a location within or
below said bed and a location above said be, to determine
changes that occur either in said weight or in said
differential pressure, and
adjusting the amount of said hydrocarbon component being
supplied as a part of said upward coating flow based upon
changes determined to have occurred either in said weight or
in said differential pressure so as to compensate for such
changes and thereby precisely regulate the rate of deposition
of pyrocarbon over time and thereby produce a precise
thickness of pyrocarbon coating of uniform crystalline
2
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