Appeal No. 1996-2857
Application 08/191,735
would indeed be provided in the process by mullite. See generally In re Piasecki, 745 F.2d 1468,
1472, 223 USPQ 785, 788 (Fed. Cir. 1984).
Turning now to Bergna ‘017, we agree with appellant (brief, page 7) that this reference does
not disclose that the fibrillar boehmite used to form the gel has a particle size smaller than about 100
nanometers as specified in claim 15. We find that the examiner has not established to the contrary
(answer, e.g., page 10, lines 1-3). Furthermore, as pointed out by appellant (brief, e.g., pages 7 and
14-15), Bergna ‘017 teaches that the intermediate alpha alumina is treated with hydrofluoric acid to
remove impurities, including, inter alia, “aluminosilicates such as mullite,” (col. 4, lines 20-33) in order
to arrive at “corundum” having the properties specified at col. 4, lines 34-48, relied on by the examiner
(answer, page 5), which product would not be a silica coated alpha alumina. We find further that
Bergna ‘017 discloses that an intermediate alpha alumina product, that is, prior to treatment with
hydrofluoric acid, prepared from a blend of fibrillar colloidal boehmite and colloidal silica will, “under
optimum conditions,” have a particle size of “about 75 millimicrons,” that is, about 75 nanometers (col.
8, lines 35-75; see also cols. 9-10, particularly, col. 10, lines 16-62).
We find no disclosure in Cottringer ‘364 which would bridge the gap between Markhoff-
Matheny ‘461 and claim 15 with respect to the issue of whether mullite would provide the requisite
silica to the boehmite gel. We further find no disclosure in Cottringer which would have suggested to
one of ordinary skill in this art that silica coated alpha alumina particles having the characteristics
specified in claims 15 and 9 could be made by the process therein, using silica (col. 6, line 56, to col. 7,
line 5). Indeed, this reference discloses the preparation of “alpha alumina particles (crystallites) of
submicron size (0.2 to 0.4 micrometers),” that is, 200 to 400 nanometers (e.g., col. 2, lines 8-15, and
Examples I to IX). Thus, we find no suggestion in Cottringer ‘364 that the teachings of either of the
other two references could be modified to result in the preparation of silica coated alpha alumina
particles having the characteristics specified in claims 9 and 15.
A discussion of Okajima ‘015 is not necessary to our decision (see brief, page 10).
Accordingly, on the record before us, it is apparent that Markhoff-Matheny ‘461, Bergna ‘017
and Cottringer ‘364, separately and combined, would not have motivated one of ordinary skill in this
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