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. 2Page: Previous 1 2 3 4 5 6 7 8 9 10 11 12 13 NextLast modified: November 3, 2007