Appeal No. 1999-1136
Application No. 08/771,373
pyrolytic boron nitride (PBN), such a boat being disclosed in
the Morris patent, infra. The basic invention is disclosed as
residing in the discovery that (page 2, lines 16 to 19):
the useful life of the vaporization boat may be
extended by increasing the density of the PBN outer
coating in contact with the metal to be vaporized to
a density above at least 2.19 gm/cc and preferably
between 2.19 gm/cc and 2.2 gm/cc.
Claim 1, the only independent claim on appeal, defines
the subject matter in issue as:
1. A flash evaporator vaporization boat comprising:
a graphite body having a recessed cavity and an outer
surface coating composed of a high density pyrolytic boron
nitride having a hexagonal crystal structure and a density
above at least 2.19 gm/cc, wherein the coating is deposited by
chemical vapor deposition at a temperature of between 1800° C
to 2200° C.
Claims 1 to 6 are reproduced in the appendix of appellants'
brief.1
The references applied in the final rejection are:
Basche 3,152,006 Oct. 6,
1964
Tanji et al. (Tanji) 4,849,146 Jul. 18,
1989
Finicle 5,158,750 Oct. 27,
1992
1 We note that in claim 3, "the metal to be vaporized" has
no antecedent basis.
2
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