Appeal No. 2001-0773
Application No. 09/200,421
specification that their departure from the prior art is
sintering the green body within the claimed temperature range
for a period of from about 8 hours to about 12 hours, rather than
4 hours. Specification Figures 3 and 4 illustrate the
differences between the same ceramic material after firing times
of 4 and 8 hours. On the other hand, each of the references
applied by the examiner utilizes a different sintering protocol
than the one employed by appellants. For instance, Rhodes
sinters at a temperature which barely touches the upper limit of
the claimed range for a maximum of 6 hours, and we cannot agree
with the examiner that the claimed "about 8 hours" encompasses
Rhodes' upper limit of 6 hours. While it has been held that
"about 10%" embraces 8%, 6 hours is 25% less than 8 hours.
As for Heytmeijer, although the reference discloses a final
sintering step of 2 to 24 hours which encompasses the claimed
time range, Heytmeijer also includes a pre-sintering step of 1 to
10 hours at about 1000°C and a final sintering step at a
temperature of 1700°-1900°C. As pointed out by appellants, the
process disclosed in the present specification does not include a
pre-sintering step.
Takahashi sinters an alumina comprising zirconium oxide and
exemplifies a sintering temperature which overlaps the claimed
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