Appeal No. 1998-2300
Application No. 08/366,762
USPQ 785, 787-88 (Fed. Cir. 1984). To that end, the examiner must show that some
objective teaching or suggestion in the applied prior art, or knowledge generally available in
the art would have led one of ordinary skill in the art to arrive at the claimed invention.
Pro-Mold & Tool Co. v. Great Lakes Plastics, Inc., 75 F.3d 1568, 1573, 37 USPQ2d
1626, 1630 (Fed. Cir. 1996).
Mehrotra discloses a method of producing pure and dense fused synthetic silica
particles from amorphous silica which exists as discrete particles. (Column 4, lines
41-43). The method includes a two step calcination which is utilized to maximize removal
of impurities and minimize devitrification. (Column 8, lines 53–59). In the first step, the
amorphous silica particles are calcined in an inert atmosphere at a temperature of at least
o
about 1000 C to increase density and volatilize impurities. (Column 3, line 58-68). In the
o o
second step, the temperature is raised, between 1250 C and 1400 C, for a short period of
time to increase the density of the silica particles. (Column 8, lines 58-60 and column 9,
lines 12-16). Mehrotra discloses inert atmosphere is important during calcination,
o
especially at temperature greater than 1000 C, so as to reduce devitrification and reduce
the formation of crystalline phases. (Column 5, lines 47-58). Mehrotra discloses water is
used as the agglomeration agent because other types of binders will leave a residue on the
agglomerated particles. (Column 5, line 65 to column 6, line 8).
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